Re: [PATCH v5 03/16] x86/mtrr: get MTRR number and support TOP_MEM2

[Pu Wen]

On 2018/9/4 3:04, Borislav Petkov wrote:
> It was "Hygon Dhyana" before now "Hygon" only. Can we agree on the
> naming nomenclature and stick with it.

OK, agree on it.

...

> > -	if (!((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
> > -	      (boot_cpu_data.x86 >= 0x0f)))
> > +	if (!((boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
> > +	       boot_cpu_data.x86 >= 0x0f) ||
> > +	       boot_cpu_data.x86_vendor == X86_VENDOR_HYGON))
>
> Why are you even touching this statement? The function returns early on
> !X86_VENDOR_AMD.

The statement is briefly equal to !(X86_VENDOR_AMD || X86_VENDOR_HYGON).
So the function will not return early on !X86_VENDOR_AMD. :-)

Also the statement can be changed to:
+	if (!(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+	      boot_cpu_data.x86 >= 0x0f) &&
+	    !(boot_cpu_data.x86_vendor == X86_VENDOR_HYGON))
or:
+	if ((boot_cpu_data.x86_vendor != X86_VENDOR_AMD ||
+	     boot_cpu_data.x86 < 0x0f) &&
+	    (boot_cpu_data.x86_vendor != X86_VENDOR_HYGON))

Which statement is better?

Thanks,
Pu Wen