deps: get rid of uhyve-interface dependency

This required making the _Note structure generic over the length of the data.

Author: fogti

Cargo.toml

@@ -26,7 +26,6 @@ goblin = { version = "0.10", default-features = false, features = ["elf64"], opt
 log = { version = "0.4", optional = true }
 plain = { version = "0.2", optional = true }
 time = { version = "0.3", default-features = false }
-uhyve-interface = "0.1"
 
 [features]
 default = []

src/elf.rs

@@ -168,7 +168,7 @@ impl TryFrom<Note<'_>> for UhyveIfVersion {
             return Err(ParseUhyveIfVersionError);
         }
 
-        if value.ty != uhyve_interface::elf::NT_UHYVE_INTERFACE_VERSION {
+        if value.ty != crate::NT_UHYVE_INTERFACE_VERSION {
             return Err(ParseUhyveIfVersionError);
         }
 

src/lib.rs

@@ -90,6 +90,10 @@ const NT_HERMIT_ENTRY_VERSION: u32 = 0x5a00;
 #[cfg_attr(not(any(feature = "loader", feature = "kernel")), expect(dead_code))]
 const HERMIT_ENTRY_VERSION: u8 = 4;
 
+/// Note type for specifying the Uhyve interface version in an elf header.
+#[cfg_attr(not(any(feature = "loader", feature = "kernel")), expect(dead_code))]
+const NT_UHYVE_INTERFACE_VERSION: u32 = 0x5b00;
+
 /// Offsets and values used to interpret the boot params ("zeropage") setup by firecracker
 /// For the full list of values see
 /// <https://github.com/torvalds/linux/blob/b6839ef26e549de68c10359d45163b0cfb031183/arch/x86/include/uapi/asm/bootparam.h#L151-L198>

src/note.rs

@@ -11,19 +11,42 @@ macro_rules! define_entry_version {
     () => {
         #[used]
         #[unsafe(link_section = ".note.hermit.entry-version")]
-        static ENTRY_VERSION: $crate::_Note = $crate::_Note::entry_version();
+        static ENTRY_VERSION: $crate::_Note<1> = $crate::_Note::entry_version();
+    };
+}
+
+/// Defines the Uhyve interface version in the note section.
+///
+/// This macro must be used in a module that is guaranteed to be linked.
+/// See <https://github.com/rust-lang/rust/issues/99721>.
+///
+/// # Examples
+///
+/// ```
+/// # mod uhyve_interface {
+/// #     pub const UHYVE_INTERFACE_VERSION: u32 = 1;
+/// # }
+/// #
+/// hermit_entry::define_uhyve_interface_version!(uhyve_interface::UHYVE_INTERFACE_VERSION);
+/// ```
+#[macro_export]
+macro_rules! define_uhyve_interface_version {
+    ($version:expr) => {
+        #[used]
+        #[unsafe(link_section = ".note.hermit.uhyve-interface-version")]
+        static INTERFACE_VERSION: $crate::_Note<4> = $crate::_Note::uhyveif_version($version);
     };
 }
 
 #[repr(C)]
 #[doc(hidden)]
-pub struct _Note {
+pub struct _Note<const N: usize> {
     header: Nhdr32,
     name: [u8; 8],
-    data: [u8; 1],
+    data: [u8; N],
 }
 
-impl _Note {
+impl _Note<1> {
     pub const fn entry_version() -> Self {
         Self {
             header: Nhdr32 {
@@ -37,6 +60,20 @@ impl _Note {
     }
 }
 
+impl _Note<4> {
+    pub const fn uhyveif_version(ver: u32) -> Self {
+        Self {
+            header: Nhdr32 {
+                n_namesz: 8,
+                n_descsz: 4,
+                n_type: crate::NT_UHYVE_INTERFACE_VERSION,
+            },
+            name: *b"UHYVEIF\0",
+            data: ver.to_be_bytes(),
+        }
+    }
+}
+
 #[repr(C)]
 struct Nhdr32 {
     n_namesz: u32,

tests/macros.rs

@@ -3,3 +3,4 @@
 
 hermit_entry::define_abi_tag!();
 hermit_entry::define_entry_version!();
+hermit_entry::define_uhyve_interface_version!(1);