diff --git a/build.rs b/build.rs
index dab64847b2b6c..75eabbba187f9 100644
--- a/build.rs
+++ b/build.rs
@@ -24,6 +24,7 @@ const ALLOWED_CFGS: &[&str] = &[
     // Corresponds to `__USE_TIME_BITS64` in UAPI
     "linux_time_bits64",
     "musl_v1_2_3",
+    "gnu_simple_baud_rates",
 ];
 
 // Extra values to allow for check-cfg.
@@ -139,6 +140,11 @@ fn main() {
         }
     }
 
+    #[cfg(target_env = "gnu")]
+    if have_symbol("GLIBC_2.42") {
+        set_cfg("gnu_simple_baud_rates");
+    }
+
     // On CI: deny all warnings
     if libc_ci {
         set_cfg("libc_deny_warnings");
@@ -288,6 +294,29 @@ fn emcc_version_code() -> Option<u64> {
     Some(major * 10000 + minor * 100 + patch)
 }
 
+/// Check if a symbol is available in the current process.
+///
+/// This can be used to detect properties of the system libc at build time.
+#[cfg(target_env = "gnu")]
+fn have_symbol(symbol: &str) -> bool {
+    use std::ffi::CString;
+    use std::os::raw::{c_char, c_void};
+    extern "C" {
+        fn dlerror() -> *const c_void;
+        fn dlsym(handle: *const c_void, symbol: *const c_char) -> *const c_void;
+    }
+    let symbol = CString::new(symbol).unwrap();
+    unsafe {
+        // Clear any error from previous dlopen/dlsym calls.
+        dlerror();
+        // Try to load the symbol.
+        // The symbol could be present but null, so ignore the return value.
+        dlsym(std::ptr::null(), symbol.as_ptr());
+        // Check that there is no new error.
+        dlerror().is_null()
+    }
+}
+
 fn set_cfg(cfg: &str) {
     assert!(
         ALLOWED_CFGS.contains(&cfg),
diff --git a/src/unix/linux_like/linux/gnu/b32/arm/mod.rs b/src/unix/linux_like/linux/gnu/b32/arm/mod.rs
index 900851ab5f42c..ff757cfe1203e 100644
--- a/src/unix/linux_like/linux/gnu/b32/arm/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/arm/mod.rs
@@ -496,39 +496,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
diff --git a/src/unix/linux_like/linux/gnu/b32/csky/mod.rs b/src/unix/linux_like/linux/gnu/b32/csky/mod.rs
index 95881894a4b94..15145e3d83291 100644
--- a/src/unix/linux_like/linux/gnu/b32/csky/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/csky/mod.rs
@@ -392,39 +392,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
diff --git a/src/unix/linux_like/linux/gnu/b32/m68k/mod.rs b/src/unix/linux_like/linux/gnu/b32/m68k/mod.rs
index d614fddeca9d9..361c08c41db9c 100644
--- a/src/unix/linux_like/linux/gnu/b32/m68k/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/m68k/mod.rs
@@ -390,39 +390,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
diff --git a/src/unix/linux_like/linux/gnu/b32/mips/mod.rs b/src/unix/linux_like/linux/gnu/b32/mips/mod.rs
index db0505a2473de..b6deac9d4187e 100644
--- a/src/unix/linux_like/linux/gnu/b32/mips/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/mips/mod.rs
@@ -887,38 +887,42 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const EHWPOISON: c_int = 168;
diff --git a/src/unix/linux_like/linux/gnu/b32/powerpc.rs b/src/unix/linux_like/linux/gnu/b32/powerpc.rs
index 791f14956806d..3544eee39d312 100644
--- a/src/unix/linux_like/linux/gnu/b32/powerpc.rs
+++ b/src/unix/linux_like/linux/gnu/b32/powerpc.rs
@@ -445,40 +445,44 @@ pub const FFDLY: crate::tcflag_t = 0o040000;
 pub const VTDLY: crate::tcflag_t = 0o200000;
 pub const XTABS: crate::tcflag_t = 0o006000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const CBAUDEX: crate::speed_t = 0o000020;
-pub const B57600: crate::speed_t = 0o0020;
-pub const B115200: crate::speed_t = 0o0021;
-pub const B230400: crate::speed_t = 0o0022;
-pub const B460800: crate::speed_t = 0o0023;
-pub const B500000: crate::speed_t = 0o0024;
-pub const B576000: crate::speed_t = 0o0025;
-pub const B921600: crate::speed_t = 0o0026;
-pub const B1000000: crate::speed_t = 0o0027;
-pub const B1152000: crate::speed_t = 0o0030;
-pub const B1500000: crate::speed_t = 0o0031;
-pub const B2000000: crate::speed_t = 0o0032;
-pub const B2500000: crate::speed_t = 0o0033;
-pub const B3000000: crate::speed_t = 0o0034;
-pub const B3500000: crate::speed_t = 0o0035;
-pub const B4000000: crate::speed_t = 0o0036;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const CBAUDEX: crate::speed_t = 0o000020;
+        pub const B57600: crate::speed_t = 0o0020;
+        pub const B115200: crate::speed_t = 0o0021;
+        pub const B230400: crate::speed_t = 0o0022;
+        pub const B460800: crate::speed_t = 0o0023;
+        pub const B500000: crate::speed_t = 0o0024;
+        pub const B576000: crate::speed_t = 0o0025;
+        pub const B921600: crate::speed_t = 0o0026;
+        pub const B1000000: crate::speed_t = 0o0027;
+        pub const B1152000: crate::speed_t = 0o0030;
+        pub const B1500000: crate::speed_t = 0o0031;
+        pub const B2000000: crate::speed_t = 0o0032;
+        pub const B2500000: crate::speed_t = 0o0033;
+        pub const B3000000: crate::speed_t = 0o0034;
+        pub const B3500000: crate::speed_t = 0o0035;
+        pub const B4000000: crate::speed_t = 0o0036;
+    }
+}
 
 pub const VEOL: usize = 6;
 pub const VEOL2: usize = 8;
diff --git a/src/unix/linux_like/linux/gnu/b32/riscv32/mod.rs b/src/unix/linux_like/linux/gnu/b32/riscv32/mod.rs
index b04ee50462745..11e7d70128ef6 100644
--- a/src/unix/linux_like/linux/gnu/b32/riscv32/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/riscv32/mod.rs
@@ -449,39 +449,45 @@ pub const BSDLY: crate::tcflag_t = 8192;
 pub const FFDLY: crate::tcflag_t = 32768;
 pub const VTDLY: crate::tcflag_t = 16384;
 pub const XTABS: crate::tcflag_t = 6144;
-pub const B0: crate::speed_t = 0;
-pub const B50: crate::speed_t = 1;
-pub const B75: crate::speed_t = 2;
-pub const B110: crate::speed_t = 3;
-pub const B134: crate::speed_t = 4;
-pub const B150: crate::speed_t = 5;
-pub const B200: crate::speed_t = 6;
-pub const B300: crate::speed_t = 7;
-pub const B600: crate::speed_t = 8;
-pub const B1200: crate::speed_t = 9;
-pub const B1800: crate::speed_t = 10;
-pub const B2400: crate::speed_t = 11;
-pub const B4800: crate::speed_t = 12;
-pub const B9600: crate::speed_t = 13;
-pub const B19200: crate::speed_t = 14;
-pub const B38400: crate::speed_t = 15;
-pub const EXTA: crate::speed_t = 14;
-pub const EXTB: crate::speed_t = 15;
-pub const B57600: crate::speed_t = 4097;
-pub const B115200: crate::speed_t = 4098;
-pub const B230400: crate::speed_t = 4099;
-pub const B460800: crate::speed_t = 4100;
-pub const B500000: crate::speed_t = 4101;
-pub const B576000: crate::speed_t = 4102;
-pub const B921600: crate::speed_t = 4103;
-pub const B1000000: crate::speed_t = 4104;
-pub const B1152000: crate::speed_t = 4105;
-pub const B1500000: crate::speed_t = 4106;
-pub const B2000000: crate::speed_t = 4107;
-pub const B2500000: crate::speed_t = 4108;
-pub const B3000000: crate::speed_t = 4109;
-pub const B3500000: crate::speed_t = 4110;
-pub const B4000000: crate::speed_t = 4111;
+
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0;
+        pub const B50: crate::speed_t = 1;
+        pub const B75: crate::speed_t = 2;
+        pub const B110: crate::speed_t = 3;
+        pub const B134: crate::speed_t = 4;
+        pub const B150: crate::speed_t = 5;
+        pub const B200: crate::speed_t = 6;
+        pub const B300: crate::speed_t = 7;
+        pub const B600: crate::speed_t = 8;
+        pub const B1200: crate::speed_t = 9;
+        pub const B1800: crate::speed_t = 10;
+        pub const B2400: crate::speed_t = 11;
+        pub const B4800: crate::speed_t = 12;
+        pub const B9600: crate::speed_t = 13;
+        pub const B19200: crate::speed_t = 14;
+        pub const B38400: crate::speed_t = 15;
+        pub const EXTA: crate::speed_t = 14;
+        pub const EXTB: crate::speed_t = 15;
+        pub const B57600: crate::speed_t = 4097;
+        pub const B115200: crate::speed_t = 4098;
+        pub const B230400: crate::speed_t = 4099;
+        pub const B460800: crate::speed_t = 4100;
+        pub const B500000: crate::speed_t = 4101;
+        pub const B576000: crate::speed_t = 4102;
+        pub const B921600: crate::speed_t = 4103;
+        pub const B1000000: crate::speed_t = 4104;
+        pub const B1152000: crate::speed_t = 4105;
+        pub const B1500000: crate::speed_t = 4106;
+        pub const B2000000: crate::speed_t = 4107;
+        pub const B2500000: crate::speed_t = 4108;
+        pub const B3000000: crate::speed_t = 4109;
+        pub const B3500000: crate::speed_t = 4110;
+        pub const B4000000: crate::speed_t = 4111;
+    }
+}
+
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
 pub const VMIN: usize = 6;
diff --git a/src/unix/linux_like/linux/gnu/b32/sparc/mod.rs b/src/unix/linux_like/linux/gnu/b32/sparc/mod.rs
index f9d6a95ed036e..29f42f0da77dc 100644
--- a/src/unix/linux_like/linux/gnu/b32/sparc/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/sparc/mod.rs
@@ -430,39 +430,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0x1001;
-pub const B115200: crate::speed_t = 0x1002;
-pub const B230400: crate::speed_t = 0x1003;
-pub const B460800: crate::speed_t = 0x1004;
-pub const B76800: crate::speed_t = 0x1005;
-pub const B153600: crate::speed_t = 0x1006;
-pub const B307200: crate::speed_t = 0x1007;
-pub const B614400: crate::speed_t = 0x1008;
-pub const B921600: crate::speed_t = 0x1009;
-pub const B500000: crate::speed_t = 0x100a;
-pub const B576000: crate::speed_t = 0x100b;
-pub const B1000000: crate::speed_t = 0x100c;
-pub const B1152000: crate::speed_t = 0x100d;
-pub const B1500000: crate::speed_t = 0x100e;
-pub const B2000000: crate::speed_t = 0x100f;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0x1001;
+        pub const B115200: crate::speed_t = 0x1002;
+        pub const B230400: crate::speed_t = 0x1003;
+        pub const B460800: crate::speed_t = 0x1004;
+        pub const B76800: crate::speed_t = 0x1005;
+        pub const B153600: crate::speed_t = 0x1006;
+        pub const B307200: crate::speed_t = 0x1007;
+        pub const B614400: crate::speed_t = 0x1008;
+        pub const B921600: crate::speed_t = 0x1009;
+        pub const B500000: crate::speed_t = 0x100a;
+        pub const B576000: crate::speed_t = 0x100b;
+        pub const B1000000: crate::speed_t = 0x100c;
+        pub const B1152000: crate::speed_t = 0x100d;
+        pub const B1500000: crate::speed_t = 0x100e;
+        pub const B2000000: crate::speed_t = 0x100f;
+    }
+}
 
 pub const VEOL: usize = 5;
 pub const VEOL2: usize = 6;
diff --git a/src/unix/linux_like/linux/gnu/b32/x86/mod.rs b/src/unix/linux_like/linux/gnu/b32/x86/mod.rs
index 5f0dfe90adf81..3be52a1ff5519 100644
--- a/src/unix/linux_like/linux/gnu/b32/x86/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b32/x86/mod.rs
@@ -589,39 +589,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
diff --git a/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs b/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
index 28b4e40fde543..d14e60011dea5 100644
--- a/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
@@ -523,39 +523,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
diff --git a/src/unix/linux_like/linux/gnu/b64/loongarch64/mod.rs b/src/unix/linux_like/linux/gnu/b64/loongarch64/mod.rs
index 8f15ce4d1529a..ad4033027b367 100644
--- a/src/unix/linux_like/linux/gnu/b64/loongarch64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/loongarch64/mod.rs
@@ -849,39 +849,45 @@ pub const HUPCL: crate::tcflag_t = 0x00000400;
 pub const CLOCAL: crate::tcflag_t = 0x00000800;
 pub const CIBAUD: crate::tcflag_t = 0o02003600000;
 pub const CBAUDEX: crate::tcflag_t = 0o010000;
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
+
 pub const TAB1: crate::tcflag_t = 0x00000800;
 pub const TAB2: crate::tcflag_t = 0x00001000;
 pub const TAB3: crate::tcflag_t = 0x00001800;
diff --git a/src/unix/linux_like/linux/gnu/b64/mips64/mod.rs b/src/unix/linux_like/linux/gnu/b64/mips64/mod.rs
index 56f30cd08a482..a9bc119ae6f72 100644
--- a/src/unix/linux_like/linux/gnu/b64/mips64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/mips64/mod.rs
@@ -881,39 +881,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const EHWPOISON: c_int = 168;
 
diff --git a/src/unix/linux_like/linux/gnu/b64/powerpc64/mod.rs b/src/unix/linux_like/linux/gnu/b64/powerpc64/mod.rs
index 047efe55b1a38..d7e0c050c90f6 100644
--- a/src/unix/linux_like/linux/gnu/b64/powerpc64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/powerpc64/mod.rs
@@ -526,40 +526,44 @@ pub const FFDLY: crate::tcflag_t = 0o040000;
 pub const VTDLY: crate::tcflag_t = 0o200000;
 pub const XTABS: crate::tcflag_t = 0o006000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const CBAUDEX: crate::speed_t = 0o000020;
-pub const B57600: crate::speed_t = 0o0020;
-pub const B115200: crate::speed_t = 0o0021;
-pub const B230400: crate::speed_t = 0o0022;
-pub const B460800: crate::speed_t = 0o0023;
-pub const B500000: crate::speed_t = 0o0024;
-pub const B576000: crate::speed_t = 0o0025;
-pub const B921600: crate::speed_t = 0o0026;
-pub const B1000000: crate::speed_t = 0o0027;
-pub const B1152000: crate::speed_t = 0o0030;
-pub const B1500000: crate::speed_t = 0o0031;
-pub const B2000000: crate::speed_t = 0o0032;
-pub const B2500000: crate::speed_t = 0o0033;
-pub const B3000000: crate::speed_t = 0o0034;
-pub const B3500000: crate::speed_t = 0o0035;
-pub const B4000000: crate::speed_t = 0o0036;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const CBAUDEX: crate::speed_t = 0o000020;
+        pub const B57600: crate::speed_t = 0o0020;
+        pub const B115200: crate::speed_t = 0o0021;
+        pub const B230400: crate::speed_t = 0o0022;
+        pub const B460800: crate::speed_t = 0o0023;
+        pub const B500000: crate::speed_t = 0o0024;
+        pub const B576000: crate::speed_t = 0o0025;
+        pub const B921600: crate::speed_t = 0o0026;
+        pub const B1000000: crate::speed_t = 0o0027;
+        pub const B1152000: crate::speed_t = 0o0030;
+        pub const B1500000: crate::speed_t = 0o0031;
+        pub const B2000000: crate::speed_t = 0o0032;
+        pub const B2500000: crate::speed_t = 0o0033;
+        pub const B3000000: crate::speed_t = 0o0034;
+        pub const B3500000: crate::speed_t = 0o0035;
+        pub const B4000000: crate::speed_t = 0o0036;
+    }
+}
 
 pub const VEOL: usize = 6;
 pub const VEOL2: usize = 8;
diff --git a/src/unix/linux_like/linux/gnu/b64/riscv64/mod.rs b/src/unix/linux_like/linux/gnu/b64/riscv64/mod.rs
index bfbc8ee5cf683..6090f940a47ea 100644
--- a/src/unix/linux_like/linux/gnu/b64/riscv64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/riscv64/mod.rs
@@ -542,39 +542,45 @@ pub const BSDLY: crate::tcflag_t = 8192;
 pub const FFDLY: crate::tcflag_t = 32768;
 pub const VTDLY: crate::tcflag_t = 16384;
 pub const XTABS: crate::tcflag_t = 6144;
-pub const B0: crate::speed_t = 0;
-pub const B50: crate::speed_t = 1;
-pub const B75: crate::speed_t = 2;
-pub const B110: crate::speed_t = 3;
-pub const B134: crate::speed_t = 4;
-pub const B150: crate::speed_t = 5;
-pub const B200: crate::speed_t = 6;
-pub const B300: crate::speed_t = 7;
-pub const B600: crate::speed_t = 8;
-pub const B1200: crate::speed_t = 9;
-pub const B1800: crate::speed_t = 10;
-pub const B2400: crate::speed_t = 11;
-pub const B4800: crate::speed_t = 12;
-pub const B9600: crate::speed_t = 13;
-pub const B19200: crate::speed_t = 14;
-pub const B38400: crate::speed_t = 15;
-pub const EXTA: crate::speed_t = 14;
-pub const EXTB: crate::speed_t = 15;
-pub const B57600: crate::speed_t = 4097;
-pub const B115200: crate::speed_t = 4098;
-pub const B230400: crate::speed_t = 4099;
-pub const B460800: crate::speed_t = 4100;
-pub const B500000: crate::speed_t = 4101;
-pub const B576000: crate::speed_t = 4102;
-pub const B921600: crate::speed_t = 4103;
-pub const B1000000: crate::speed_t = 4104;
-pub const B1152000: crate::speed_t = 4105;
-pub const B1500000: crate::speed_t = 4106;
-pub const B2000000: crate::speed_t = 4107;
-pub const B2500000: crate::speed_t = 4108;
-pub const B3000000: crate::speed_t = 4109;
-pub const B3500000: crate::speed_t = 4110;
-pub const B4000000: crate::speed_t = 4111;
+
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0;
+        pub const B50: crate::speed_t = 1;
+        pub const B75: crate::speed_t = 2;
+        pub const B110: crate::speed_t = 3;
+        pub const B134: crate::speed_t = 4;
+        pub const B150: crate::speed_t = 5;
+        pub const B200: crate::speed_t = 6;
+        pub const B300: crate::speed_t = 7;
+        pub const B600: crate::speed_t = 8;
+        pub const B1200: crate::speed_t = 9;
+        pub const B1800: crate::speed_t = 10;
+        pub const B2400: crate::speed_t = 11;
+        pub const B4800: crate::speed_t = 12;
+        pub const B9600: crate::speed_t = 13;
+        pub const B19200: crate::speed_t = 14;
+        pub const B38400: crate::speed_t = 15;
+        pub const EXTA: crate::speed_t = 14;
+        pub const EXTB: crate::speed_t = 15;
+        pub const B57600: crate::speed_t = 4097;
+        pub const B115200: crate::speed_t = 4098;
+        pub const B230400: crate::speed_t = 4099;
+        pub const B460800: crate::speed_t = 4100;
+        pub const B500000: crate::speed_t = 4101;
+        pub const B576000: crate::speed_t = 4102;
+        pub const B921600: crate::speed_t = 4103;
+        pub const B1000000: crate::speed_t = 4104;
+        pub const B1152000: crate::speed_t = 4105;
+        pub const B1500000: crate::speed_t = 4106;
+        pub const B2000000: crate::speed_t = 4107;
+        pub const B2500000: crate::speed_t = 4108;
+        pub const B3000000: crate::speed_t = 4109;
+        pub const B3500000: crate::speed_t = 4110;
+        pub const B4000000: crate::speed_t = 4111;
+    }
+}
+
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
 pub const VMIN: usize = 6;
diff --git a/src/unix/linux_like/linux/gnu/b64/s390x.rs b/src/unix/linux_like/linux/gnu/b64/s390x.rs
index 583630ed37c74..930848852c2cf 100644
--- a/src/unix/linux_like/linux/gnu/b64/s390x.rs
+++ b/src/unix/linux_like/linux/gnu/b64/s390x.rs
@@ -515,51 +515,55 @@ pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const VT1: crate::tcflag_t = 0x00004000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const CBAUD: crate::speed_t = 0o010017;
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const CSIZE: crate::tcflag_t = 0o000060;
-pub const CS6: crate::tcflag_t = 0o000020;
-pub const CS7: crate::tcflag_t = 0o000040;
-pub const CS8: crate::tcflag_t = 0o000060;
-pub const CSTOPB: crate::tcflag_t = 0o000100;
-pub const CREAD: crate::tcflag_t = 0o000200;
-pub const PARENB: crate::tcflag_t = 0o000400;
-pub const PARODD: crate::tcflag_t = 0o001000;
-pub const HUPCL: crate::tcflag_t = 0o002000;
-pub const CLOCAL: crate::tcflag_t = 0o004000;
-pub const CBAUDEX: crate::tcflag_t = 0o010000;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const CBAUD: crate::speed_t = 0o010017;
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const CSIZE: crate::tcflag_t = 0o000060;
+        pub const CS6: crate::tcflag_t = 0o000020;
+        pub const CS7: crate::tcflag_t = 0o000040;
+        pub const CS8: crate::tcflag_t = 0o000060;
+        pub const CSTOPB: crate::tcflag_t = 0o000100;
+        pub const CREAD: crate::tcflag_t = 0o000200;
+        pub const PARENB: crate::tcflag_t = 0o000400;
+        pub const PARODD: crate::tcflag_t = 0o001000;
+        pub const HUPCL: crate::tcflag_t = 0o002000;
+        pub const CLOCAL: crate::tcflag_t = 0o004000;
+        pub const CBAUDEX: crate::tcflag_t = 0o010000;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 pub const CIBAUD: crate::tcflag_t = 0o02003600000;
 
 pub const ISIG: crate::tcflag_t = 0o000001;
diff --git a/src/unix/linux_like/linux/gnu/b64/sparc64/mod.rs b/src/unix/linux_like/linux/gnu/b64/sparc64/mod.rs
index c4203dc0b2da4..e6d9cb152b739 100644
--- a/src/unix/linux_like/linux/gnu/b64/sparc64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/sparc64/mod.rs
@@ -502,39 +502,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0x1001;
-pub const B115200: crate::speed_t = 0x1002;
-pub const B230400: crate::speed_t = 0x1003;
-pub const B460800: crate::speed_t = 0x1004;
-pub const B76800: crate::speed_t = 0x1005;
-pub const B153600: crate::speed_t = 0x1006;
-pub const B307200: crate::speed_t = 0x1007;
-pub const B614400: crate::speed_t = 0x1008;
-pub const B921600: crate::speed_t = 0x1009;
-pub const B500000: crate::speed_t = 0x100a;
-pub const B576000: crate::speed_t = 0x100b;
-pub const B1000000: crate::speed_t = 0x100c;
-pub const B1152000: crate::speed_t = 0x100d;
-pub const B1500000: crate::speed_t = 0x100e;
-pub const B2000000: crate::speed_t = 0x100f;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0x1001;
+        pub const B115200: crate::speed_t = 0x1002;
+        pub const B230400: crate::speed_t = 0x1003;
+        pub const B460800: crate::speed_t = 0x1004;
+        pub const B76800: crate::speed_t = 0x1005;
+        pub const B153600: crate::speed_t = 0x1006;
+        pub const B307200: crate::speed_t = 0x1007;
+        pub const B614400: crate::speed_t = 0x1008;
+        pub const B921600: crate::speed_t = 0x1009;
+        pub const B500000: crate::speed_t = 0x100a;
+        pub const B576000: crate::speed_t = 0x100b;
+        pub const B1000000: crate::speed_t = 0x100c;
+        pub const B1152000: crate::speed_t = 0x100d;
+        pub const B1500000: crate::speed_t = 0x100e;
+        pub const B2000000: crate::speed_t = 0x100f;
+    }
+}
 
 pub const VEOL: usize = 5;
 pub const VEOL2: usize = 6;
diff --git a/src/unix/linux_like/linux/gnu/b64/x86_64/mod.rs b/src/unix/linux_like/linux/gnu/b64/x86_64/mod.rs
index f4555ee420230..39f1fe39ceba4 100644
--- a/src/unix/linux_like/linux/gnu/b64/x86_64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/x86_64/mod.rs
@@ -695,39 +695,43 @@ pub const FFDLY: crate::tcflag_t = 0o100000;
 pub const VTDLY: crate::tcflag_t = 0o040000;
 pub const XTABS: crate::tcflag_t = 0o014000;
 
-pub const B0: crate::speed_t = 0o000000;
-pub const B50: crate::speed_t = 0o000001;
-pub const B75: crate::speed_t = 0o000002;
-pub const B110: crate::speed_t = 0o000003;
-pub const B134: crate::speed_t = 0o000004;
-pub const B150: crate::speed_t = 0o000005;
-pub const B200: crate::speed_t = 0o000006;
-pub const B300: crate::speed_t = 0o000007;
-pub const B600: crate::speed_t = 0o000010;
-pub const B1200: crate::speed_t = 0o000011;
-pub const B1800: crate::speed_t = 0o000012;
-pub const B2400: crate::speed_t = 0o000013;
-pub const B4800: crate::speed_t = 0o000014;
-pub const B9600: crate::speed_t = 0o000015;
-pub const B19200: crate::speed_t = 0o000016;
-pub const B38400: crate::speed_t = 0o000017;
-pub const EXTA: crate::speed_t = B19200;
-pub const EXTB: crate::speed_t = B38400;
-pub const B57600: crate::speed_t = 0o010001;
-pub const B115200: crate::speed_t = 0o010002;
-pub const B230400: crate::speed_t = 0o010003;
-pub const B460800: crate::speed_t = 0o010004;
-pub const B500000: crate::speed_t = 0o010005;
-pub const B576000: crate::speed_t = 0o010006;
-pub const B921600: crate::speed_t = 0o010007;
-pub const B1000000: crate::speed_t = 0o010010;
-pub const B1152000: crate::speed_t = 0o010011;
-pub const B1500000: crate::speed_t = 0o010012;
-pub const B2000000: crate::speed_t = 0o010013;
-pub const B2500000: crate::speed_t = 0o010014;
-pub const B3000000: crate::speed_t = 0o010015;
-pub const B3500000: crate::speed_t = 0o010016;
-pub const B4000000: crate::speed_t = 0o010017;
+cfg_if! {
+    if #[cfg(not(gnu_simple_baud_rates))] {
+        pub const B0: crate::speed_t = 0o000000;
+        pub const B50: crate::speed_t = 0o000001;
+        pub const B75: crate::speed_t = 0o000002;
+        pub const B110: crate::speed_t = 0o000003;
+        pub const B134: crate::speed_t = 0o000004;
+        pub const B150: crate::speed_t = 0o000005;
+        pub const B200: crate::speed_t = 0o000006;
+        pub const B300: crate::speed_t = 0o000007;
+        pub const B600: crate::speed_t = 0o000010;
+        pub const B1200: crate::speed_t = 0o000011;
+        pub const B1800: crate::speed_t = 0o000012;
+        pub const B2400: crate::speed_t = 0o000013;
+        pub const B4800: crate::speed_t = 0o000014;
+        pub const B9600: crate::speed_t = 0o000015;
+        pub const B19200: crate::speed_t = 0o000016;
+        pub const B38400: crate::speed_t = 0o000017;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 0o010001;
+        pub const B115200: crate::speed_t = 0o010002;
+        pub const B230400: crate::speed_t = 0o010003;
+        pub const B460800: crate::speed_t = 0o010004;
+        pub const B500000: crate::speed_t = 0o010005;
+        pub const B576000: crate::speed_t = 0o010006;
+        pub const B921600: crate::speed_t = 0o010007;
+        pub const B1000000: crate::speed_t = 0o010010;
+        pub const B1152000: crate::speed_t = 0o010011;
+        pub const B1500000: crate::speed_t = 0o010012;
+        pub const B2000000: crate::speed_t = 0o010013;
+        pub const B2500000: crate::speed_t = 0o010014;
+        pub const B3000000: crate::speed_t = 0o010015;
+        pub const B3500000: crate::speed_t = 0o010016;
+        pub const B4000000: crate::speed_t = 0o010017;
+    }
+}
 
 pub const VEOL: usize = 11;
 pub const VEOL2: usize = 16;
diff --git a/src/unix/linux_like/linux/gnu/mod.rs b/src/unix/linux_like/linux/gnu/mod.rs
index 86ade8f04173e..925000c37c48c 100644
--- a/src/unix/linux_like/linux/gnu/mod.rs
+++ b/src/unix/linux_like/linux/gnu/mod.rs
@@ -65,23 +65,31 @@ s! {
         pub c_lflag: crate::tcflag_t,
         pub c_line: crate::cc_t,
         pub c_cc: [crate::cc_t; crate::NCCS],
-        #[cfg(not(any(
-            target_arch = "sparc",
-            target_arch = "sparc64",
-            target_arch = "mips",
-            target_arch = "mips32r6",
-            target_arch = "mips64",
-            target_arch = "mips64r6"
-        )))]
+        /// For the sparc and mips architecture, this field if available on glibc 2.42 and higher.
+        #[cfg(any(
+            gnu_simple_baud_rates,
+            not(any(
+                target_arch = "sparc",
+                target_arch = "sparc64",
+                target_arch = "mips",
+                target_arch = "mips32r6",
+                target_arch = "mips64",
+                target_arch = "mips64r6"
+            ))
+        ))]
         pub c_ispeed: crate::speed_t,
-        #[cfg(not(any(
-            target_arch = "sparc",
-            target_arch = "sparc64",
-            target_arch = "mips",
-            target_arch = "mips32r6",
-            target_arch = "mips64",
-            target_arch = "mips64r6"
-        )))]
+        /// For the sparc and mips architecture, this field if available on glibc 2.42 and higher.
+        #[cfg(any(
+            gnu_simple_baud_rates,
+            not(any(
+                target_arch = "sparc",
+                target_arch = "sparc64",
+                target_arch = "mips",
+                target_arch = "mips32r6",
+                target_arch = "mips64",
+                target_arch = "mips64r6"
+            ))
+        ))]
         pub c_ospeed: crate::speed_t,
     }
 
@@ -1045,6 +1053,48 @@ pub const REG_EEND: c_int = 14;
 pub const REG_ESIZE: c_int = 15;
 pub const REG_ERPAREN: c_int = 16;
 
+cfg_if! {
+    if #[cfg(gnu_simple_baud_rates)] {
+        pub const B0: crate::speed_t = 0;
+        pub const B50: crate::speed_t = 50;
+        pub const B75: crate::speed_t = 75;
+        pub const B110: crate::speed_t = 110;
+        pub const B134: crate::speed_t = 134;
+        pub const B150: crate::speed_t = 150;
+        pub const B200: crate::speed_t = 200;
+        pub const B300: crate::speed_t = 300;
+        pub const B600: crate::speed_t = 600;
+        pub const B1200: crate::speed_t = 1200;
+        pub const B1800: crate::speed_t = 1800;
+        pub const B2400: crate::speed_t = 2400;
+        pub const B4800: crate::speed_t = 4800;
+        pub const B9600: crate::speed_t = 9600;
+        pub const B19200: crate::speed_t = 19200;
+        pub const B38400: crate::speed_t = 38400;
+        pub const EXTA: crate::speed_t = B19200;
+        pub const EXTB: crate::speed_t = B38400;
+        pub const B57600: crate::speed_t = 57600;
+        pub const B115200: crate::speed_t = 115200;
+        pub const B230400: crate::speed_t = 230400;
+        pub const B460800: crate::speed_t = 460800;
+        pub const B500000: crate::speed_t = 500000;
+        pub const B576000: crate::speed_t = 576000;
+        pub const B921600: crate::speed_t = 921600;
+        pub const B1000000: crate::speed_t = 1000000;
+        pub const B1152000: crate::speed_t = 1152000;
+        pub const B1500000: crate::speed_t = 1500000;
+        pub const B2000000: crate::speed_t = 2000000;
+        cfg_if! {
+            if #[cfg(not(any(target_arch = "sparc", target_arch = "sparc64")))] {
+                pub const B2500000: crate::speed_t = 2500000;
+                pub const B3000000: crate::speed_t = 3000000;
+                pub const B3500000: crate::speed_t = 3500000;
+                pub const B4000000: crate::speed_t = 4000000;
+            }
+        }
+    }
+}
+
 extern "C" {
     pub fn fgetspent_r(
         fp: *mut crate::FILE,