Re: [PATCH 4/8] x86/intel_rdt/mba: Memory b/w allocation feature detect

From: Thomas Gleixner
Date: Mon Jan 16 2017 - 08:59:21 EST


On Tue, 10 Jan 2017, Vikas Shivappa wrote:

> Detect MBA feature if CPUID.(EAX=10H, ECX=0):EBX.L2[bit 3] = 1.
> Add supporting data structures to detect feature details which is done
> in later patch using CPUID with EAX=10H, ECX= 3.

So why is the $subject of this patch claiming that it provides the feature
detection?

> -/* CPUID.(EAX=10H, ECX=ResID=1).EDX */
> +/* CPUID.(EAX=10H, ECX=ResID=3).EAX */
> +union cpuid_0x10_3_eax {
> + struct {
> + unsigned int max_delay:12;
> + } split;

And the point of this struct is?

> + unsigned int full;
> +};

> + if (boot_cpu_has(X86_FEATURE_MBA)) {
> + ret = true;
> + }

Pointless brackets.

Thanks,

tglx