glibc/sysdeps/x86_64/multiarch/init-arch.c
Ulrich Drepper 963cb6fcb4 Simplify CPUID value handling.
SO far Intel and AMD use exactly the same bits meaning the same
things in CPUID index 1.  Simplify the code.  Should an architecture
come along which doesn't use the same semantics then it must use a
different index value than COMMON_CPUID_INDEX_1.
2009-05-31 17:52:05 -07:00

62 lines
1.9 KiB
C

/* Initialize CPU feature data.
This file is part of the GNU C Library.
Copyright (C) 2008, 2009 Free Software Foundation, Inc.
Contributed by Ulrich Drepper <drepper@redhat.com>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include "init-arch.h"
struct cpu_features __cpu_features attribute_hidden;
void
__init_cpu_features (void)
{
unsigned int ebx;
unsigned int ecx;
unsigned int edx;
asm volatile ("cpuid"
: "=a" (__cpu_features.max_cpuid), "=b" (ebx), "=c" (ecx),
"=d" (edx)
: "0" (0));
/* This spells out "GenuineIntel". */
if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
{
__cpu_features.kind = arch_kind_intel;
get_common_cpuid:
asm volatile ("cpuid"
: "=a" (__cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax),
"=b" (__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ebx),
"=c" (__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx),
"=d" (__cpu_features.cpuid[COMMON_CPUID_INDEX_1].edx)
: "0" (1));
}
/* This spells out "AuthenticAMD". */
else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
{
__cpu_features.kind = arch_kind_amd;
goto get_common_cpuid;
}
else
__cpu_features.kind = arch_kind_other;
}