Re: [PATCH v13 01/12] xen/common: add cache coloring common code

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

Hi Julien,

Thanks for your response.

On Tue, Nov 11, 2025 at 1:02 AM Julien Grall <julien@xxxxxxx> wrote:
>
> Hi Mykola,
>
> On 07/11/2025 08:27, Mykola Kvach wrote:
> >> +void __init llc_coloring_init(void)
> >> +{
> >> +    unsigned int way_size;
> >> +
> >> +    llc_coloring_enabled = (opt_llc_coloring >= 1);
> >> +    if ( (opt_llc_coloring != 0) && llc_size && llc_nr_ways )
> >> +    {
> >> +        llc_coloring_enabled = true;
> >> +        way_size = llc_size / llc_nr_ways;
> >> +    }
> >> +    else if ( !llc_coloring_enabled )
> >> +        return;
> >> +    else
> >> +    {
> >> +        way_size = get_llc_way_size();
> >> +        if ( !way_size )
> >> +            panic("LLC probing failed and 'llc-size' or 'llc-nr-ways'
> >> missing\n");
> >
> > As far as I can see, this error means that we did not detect a suitable
> > LLC/unified cache.
> > Maybe it would be better to make that explicit in the panic message.
>
> I am rather confused why there are reviews on the series that was merged
> nearly a year ago. If you have comments that needs to be addressed, then
> it would be best to either send a new series or start a new thread (if
> there are bugs which needs discussion).

I wasn’t reviewing this specific series, but rather the code in
mainline. I needed to understand whether the LLC coloring code could
impact suspend/resume (s2ram) functionality, because one of my TODO
items was to check and test the interaction between s2ram and LLC
coloring.

During this testing I noticed a few potential problems and had some
questions. Then I found the corresponding mailing list series and saw
that the part I was interested in has not changed since it was
merged, so I replied directly to that thread because the context
still matches the current mainline code.

At the time this felt like the quickest way to ask questions in the
right context without duplicating it. I understand now that this is
not the preferred workflow for this project. In the near future I
will start a new discussion thread about my findings, or possibly
send patches if I manage to address some of them myself.

Thank you.

>
> Cheers,
>
> --
> Julien Grall
>

Best regards,
Mykola