Re: [Qemu-devel] [PATCH 1/3] [x86] Clean up vendor identification

[M. Warner Losh]

In message: <address@hidden>
            Laurent Vivier <address@hidden> writes:
: Le lundi 11 août 2008 à 14:32 +0200, Alexander Graf a écrit :
: > On Aug 11, 2008, at 1:56 PM, Laurent Vivier wrote:
: > 
: > > Le lundi 11 août 2008 à 12:37 +0200, Alexander Graf a écrit :
: > >> Right now CPU vendor identification contains a lot of magic numbers.
: > >> The
: > >> patch cleans them up to defines, so we can identify the CPU later on
: > >> without copying magic numbers.
: > >>
: > >> Signed-off-by: Alexander Graf <address@hidden>
: > >>
: > >>
: > >>
: > >> diff --git a/qemu/target-i386/cpu.h b/qemu/target-i386/cpu.h
: > >> index 7e95900..3c84dc9 100644
: > >> --- a/qemu/target-i386/cpu.h
: > >> +++ b/qemu/target-i386/cpu.h
: > >> @@ -339,6 +341,14 @@
: > >> #define CPUID_EXT3_IBS     (1 << 10)
: > >> #define CPUID_EXT3_SKINIT  (1 << 12)
: > >>
: > >> +#define CPUID_VENDOR_INTEL_1 0x756e6547 /* "Genu" */
: > >> +#define CPUID_VENDOR_INTEL_2 0x49656e69 /* "ineI" */
: > >> +#define CPUID_VENDOR_INTEL_3 0x6c65746e /* "ntel" */
: > >> +
: > >> +#define CPUID_VENDOR_AMD_1   0x68747541 /* "Auth" */
: > >> +#define CPUID_VENDOR_AMD_2   0x69746e65 /* "enti" */
: > >> +#define CPUID_VENDOR_AMD_3   0x444d4163 /* "cAMD" */
: > >
: > > if you add "-Wno-multichar" in C flags, you can use:
: > >
: > > #define CPUID_VENDOR_INTEL_1 'Genu'
: > > ...
: > 
: > Is that a real improvement? It won't make the code faster and the  
: > readability doesn't improve that much either.
: 
: The code is not faster, it is not more readable,
: but when you read this, are you sure 0x756e6547 is equal to "Genu" ?
: 
: Personally, I'm not.

man ascii

and you'll be sure...  Besides, you know you have an upper case
letter, followed by 3 lower case ones just by glancing at it...

Warner