[PATCH] Cygwin: cpuid: add AArch64 build stubs

[Thirumalai Nagalingam]

Hi,

This patch adds minimal AArch64 stubs to winsup/cygwin/local_includes/cpuid.h
to allow the header to compile for the Cygwin AArch64 target.


  *
Conditional handling for aarch64 is added alongside the existing x86_64 code.
  *
The cpuid() helper returns zeroed values, and can_set_flag()
is stubbed out for AArch64.
  *
No functional CPU feature detection is implemented.
  *
The change is intended solely to unblock the AArch64 build and will require
proper architecture-specific implementations in a follow-up patch.

Thanks & regards
Thirumalai Nagalingam

In-lined patch:

diff --git a/winsup/cygwin/local_includes/cpuid.h 
b/winsup/cygwin/local_includes/cpuid.h
index 6dbb1bddf..238c88777 100644
--- a/winsup/cygwin/local_includes/cpuid.h
+++ b/winsup/cygwin/local_includes/cpuid.h
@@ -13,17 +13,23 @@ static inline void __attribute ((always_inline))
 cpuid (uint32_t *a, uint32_t *b, uint32_t *c, uint32_t *d, uint32_t ain,
        uint32_t cin = 0)
 {
+#if defined(__x86_64__)
   asm volatile ("cpuid"
                : "=a" (*a), "=b" (*b), "=c" (*c), "=d" (*d)
                : "a" (ain), "c" (cin));
+#elif defined(__aarch64__)
+  // TODO
+  *a = *b = *c = *d = 0;
+#endif
 }

-#ifdef __x86_64__
+#if defined(__x86_64__) || defined(__aarch64__)
 static inline bool __attribute ((always_inline))
 can_set_flag (uint32_t long flag)
 {
   uint32_t long r1, r2;

+#if defined(__x86_64__)
   asm volatile ("pushfq\n"
                "popq %0\n"
                "movq %0, %1\n"
@@ -37,6 +43,9 @@ can_set_flag (uint32_t long flag)
                : "=&r" (r1), "=&r" (r2)
                : "ir" (flag)
   );
+#elif defined(__aarch64__)
+  // TODO
+#endif
   return ((r1 ^ r2) & flag) != 0;
 }
 #else
--

Cygwin-cpuid-add-AArch64-build-stubs.patch
Description: Cygwin-cpuid-add-AArch64-build-stubs.patch