Re: [Xen-devel] [PATCH 1/4] libx86: Introduce x86_cpuid_lookup_vendor()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.03.19 at 15:23, <jgross@xxxxxxxx> wrote:
> IMO especially in the CPUID case it is desirable to explicitly specify
> the width of the data. Looking at nodes 0x80000002 and following this
> should be rather clear (and I even think get_model_name() should be
> modified to use a pointer to uint32_t instead of unsigned int). Using
> a type with size >= 4 doesn't fit really well. You want size == 4.

Why? Fixed width types only introduce unnecessary restrictions
when wanting to re-use code in other environments. And I don't
see why CPUID nodes 0x8000000[234] would be any better (or
worse) as an example here. If anything they tell us that neither
uint32_t nor unsigned int are right, and it should be char[4] or
uint8_t[4] instead (depending on whether we want to tie
ourselves to CHAR_BIT == 8, which clearly is more restrictive
than sizeof(int) >= 4, but otoh is also less likely to get in the
way).

Jan



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