libc/picolibc: When !TLS, use zephyr errno

For targets without thread local storage, we need to use the builtin
per-thread errno support provided by Zephyr as the multi-thread errno
support provided in picolibc relies on TLS.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

lib/libc/Kconfig

@@ -38,8 +38,8 @@ config MINIMAL_LIBC
 
 config PICOLIBC
 	bool "Picolibc library"
-	select LIBC_ERRNO
 	select THREAD_LOCAL_STORAGE if ARCH_HAS_THREAD_LOCAL_STORAGE
+	select LIBC_ERRNO if THREAD_LOCAL_STORAGE
 	depends on !NATIVE_APPLICATION
 	help
 	  Build with picolibc library. The picolibc library is built as

lib/libc/picolibc/libc-hooks.c

@@ -448,3 +448,17 @@ void abort(void)
 	k_panic();
 	CODE_UNREACHABLE;
 }
+
+#ifndef CONFIG_LIBC_ERRNO
+
+/*
+ * Picolibc needs to be able to declare this itself so that the library
+ * doesn't end up needing zephyr header files. That means using a regular
+ * function instead of an inline.
+ */
+int *z_errno_wrap(void)
+{
+	return z_errno();
+}
+
+#endif

west.yml

@@ -198,7 +198,7 @@ manifest:
       path: modules/lib/openthread
     - name: picolibc
       path: modules/lib/picolibc
-      revision: 4f8076520240192be284843a114c92853e29bbbc
+      revision: e87b2fc37345a62361478f0a6efd140e14180ba5
     - name: segger
       revision: 3a52ab222133193802d3c3b4d21730b9b1f1d2f6
       path: modules/debug/segger