diff options
Diffstat (limited to 'src/arch/x86/include/ipxe/cpuid.h')
| -rw-r--r-- | src/arch/x86/include/ipxe/cpuid.h | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/src/arch/x86/include/ipxe/cpuid.h b/src/arch/x86/include/ipxe/cpuid.h index a9df9f0d..0ae572da 100644 --- a/src/arch/x86/include/ipxe/cpuid.h +++ b/src/arch/x86/include/ipxe/cpuid.h @@ -66,19 +66,20 @@ struct x86_features { /** * Issue CPUID instruction * - * @v function CPUID function + * @v function CPUID function (input via %eax) + * @v subfunction CPUID subfunction (input via %ecx) * @v eax Output via %eax * @v ebx Output via %ebx * @v ecx Output via %ecx * @v edx Output via %edx */ static inline __attribute__ (( always_inline )) void -cpuid ( uint32_t function, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, - uint32_t *edx ) { +cpuid ( uint32_t function, uint32_t subfunction, uint32_t *eax, uint32_t *ebx, + uint32_t *ecx, uint32_t *edx ) { __asm__ ( "cpuid" : "=a" ( *eax ), "=b" ( *ebx ), "=c" ( *ecx ), "=d" ( *edx ) - : "0" ( function ) ); + : "0" ( function ), "2" ( subfunction ) ); } extern int cpuid_supported ( uint32_t function ); |