Re: [Qemu-devel] [PATCH v2 1/2] SMBIOS: Fix endian-ness when populating fields wider than 8-bit

[Paolo Bonzini <pbonzini@redhat.com>]

Il 13/05/2014 22:21, Gabriel L. Somlo ha scritto:
>>> > >-    t->processor_id[0] = smbios_cpuid_version;
>>> > >-    t->processor_id[1] = smbios_cpuid_features;
>>> > >+    t->processor_id[0] = smbios_cpuid_version; /* opaque, no cpu_to_le16 */
>>> > >+    t->processor_id[1] = smbios_cpuid_features; /* opaque, no cpu_to_le16 */
>> >
>> > Actually I think these should be subject to cpu_to_le32.  They
>> > correspond to CPUID values, so they are little-endian 32-bit.
> Right, my comment is wrong, should be "no need for cpu_to_le32()" instead
> of what I said ("no need for cpu_to_le16()")... :)
>
> Re. why I said "opaque, no need for endianness fix" is because they're
> a straight-through assignment from cpu->env.cpuid_version and
> cpu->env.features[FEAT_1_EDX], respectively. So they're not really
> "numbers" which need endianness adjustment.
>
> Did I get that wrong ? (I mean, besides the 16 vs. 32 in the comment) ?

I think they do need cpu_to_le32.  We assign them straight from other 
32-bit integers, but still bits 0..7 should be in byte 0, bits 8..15 
should be in byte 1, etc.  So we need to convert from host CPU 
endianness to target CPU endianness.

Paolo