1 files changed, 38 insertions, 0 deletions
diff --git a/roms/ipxe/src/arch/i386/include/bits/compiler.h b/roms/ipxe/src/arch/i386/include/bits/compiler.h
new file mode 100644
index 00000000..d48b4b38
--- /dev/null
+++ b/roms/ipxe/src/arch/i386/include/bits/compiler.h
@@ -0,0 +1,38 @@
+#ifndef _BITS_COMPILER_H
+#define _BITS_COMPILER_H
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#ifndef ASSEMBLY
+
+/** Declare a function with standard calling conventions */
+#define __asmcall __attribute__ (( cdecl, regparm(0) ))
+
+/**
+ * Declare a function with libgcc implicit linkage
+ *
+ * It seems as though gcc expects its implicit arithmetic functions to
+ * be cdecl, even if -mrtd is specified.  This is somewhat
+ * inconsistent; for example, if -mregparm=3 is used then the implicit
+ * functions do become regparm(3).
+ *
+ * The implicit calls to memcpy() and memset() which gcc can generate
+ * do not seem to have this inconsistency; -mregparm and -mrtd affect
+ * them in the same way as any other function.
+ *
+ * Update (25/4/14): it appears that more recent gcc versions do allow
+ * -mrtd to affect calls to the implicit arithmetic functions.  There
+ * is nothing obvious in the gcc changelogs to indicate precisely when
+ * this happened.  From experimentation with available gcc versions,
+ * the change occurred sometime between v4.6.3 and v4.7.2.  We assume
+ * that only versions up to v4.6.x require the special treatment.
+ */
+#if ( __GNUC__ < 4 ) || ( ( __GNUC__ == 4 ) && ( __GNUC_MINOR__ <= 6 ) )
+#define __libgcc __attribute__ (( cdecl ))
+#else
+#define __libgcc
+#endif
+
+#endif /* ASSEMBLY */
+
+#endif /* _BITS_COMPILER_H */