[patch #8730] Fixes for AX_EXT / AX_GCC_X86_AVX_XGETBV / AX_GCC_X86_CPUID

[Michael Petch]

URL:
  <http://savannah.gnu.org/patch/?8730>

                 Summary: Fixes for AX_EXT / AX_GCC_X86_AVX_XGETBV /
AX_GCC_X86_CPUID
                 Project: GNU Autoconf Archive
            Submitted by: mdpetch
            Submitted on: Wed 26 Aug 2015 18:50:41 MDT
                Priority: 7 - High
                  Status: None
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

An issue was discovered when CPUID was 0x07. the returned values
(eax,ebx,ecx,edx) always returned 0 even on newer processors. Some of the
CPUID categories (including 0x07) now require ECX to be set with a count value
prior to executing CPUID.

Resolved this (and other cleanup) by adding a new function
AX_GCC_X86_CPUID_COUNT(OP, COUNT); modify AX_EXT to call this new function;
and explicitly set ECX to 0 when someone calls AX_GCC_X86_CPUID; make sure
that all the __asm__ instructions include __volatile__ to be on the safe
side.

The included patch can be applied to the latest versions in git.




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File Attachments:


-------------------------------------------------------
Date: Wed 26 Aug 2015 18:50:41 MDT  Name: ax_ext_related_fixes.patch  Size:
5kB   By: mdpetch
Patch to resolve a CPUID category of 0x07 + cleanup
<http://savannah.gnu.org/patch/download.php?file_id=34749>

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