Re: [Xen-devel] [PATCH v2 04/15] x86: implement data structure and CPU init flow for MBA

[Roger Pau Monn� <roger.pau@xxxxxxxxxx>]

On Wed, Aug 30, 2017 at 01:31:51PM +0800, Yi Sun wrote:
> On 17-08-29 14:44:32, Roger Pau Monn� wrote:
> > On Thu, Aug 24, 2017 at 09:14:38AM +0800, Yi Sun wrote:
> > > +#define MBA_LINEAR         (1u << 2)
> > 
> > Why is this shifted by 2?
> > 
> This is used to mask ECX register to know if MBA linear mode is set or not.

Shouldn't this be in asm-x86/psr.h since it's part of the hardware
interface?

> > > +    /* We reserve cos=0 as default thrtl (0) which means no delay. */
> > > +    feat->cos_reg_val[0] = 0;
> > > +    wrmsrl(MSR_IA32_PSR_MBA_MASK(0), 0);
> > > +
> > > +    /* Add this feature into array. */
> > > +    info->features[type] = feat;
> > > +
> > > +    if ( !opt_cpu_info )
> > > +        return 0;
> > > +
> > > +    printk(XENLOG_INFO "MBA: enabled on socket %u, cos_max:%u,"
> > > +           "thrtl_max:%u, linear:%u.\n",
> > 
> > Please try to avoid splitting messages, it makes it hard to grep for
> > them afterward.
> > 
> Ok, but that would exceed 80 characters. Is that acceptable?

That's fine for log messages. Please add a newline after XENLOG_INFO
and align the start of the string to the start of XENLOG_INFO.

Roger.

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