Re: [PATCH 06/16] xen/arm: Introduce system suspend config option

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

Hi,

On Thu, Mar 13, 2025 at 5:37 PM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 05.03.2025 10:11, Mykola Kvach wrote:
> > --- a/xen/arch/arm/Kconfig
> > +++ b/xen/arch/arm/Kconfig
> > @@ -475,6 +475,17 @@ config ARM64_HARDEN_BRANCH_PREDICTOR
> >  config ARM32_HARDEN_BRANCH_PREDICTOR
> >      def_bool y if ARM_32 && HARDEN_BRANCH_PREDICTOR
> >
> > +config SYSTEM_SUSPEND
> > +     bool "System suspend support"
> > +     default y
> > +     depends on ARM_64
> > +     help
> > +       This option enables the system suspend support. This is the
> > +       mechanism that allows the system to be suspended to RAM and
> > +       later resumed.
> > +
> > +       If unsure, say Y.
>
> I wonder if something like this makes sense to place in an arch-specific

Maybe it makes sense, but only if we are not planning to cover
suspend/resume related code for x86 as well.

> Kconfig. It's also not becoming clear here why only Arm64 would permit it.

If I understand your comment correctly, you’re suggesting that we
could use this for x86 as well. However, in that case, we would need
to make a lot of changes in other places that are not related to this
patch series, which is specifically focused on adding suspend/resume
support for Arm64. I believe that is outside the scope of this patch
series. However, this config was requested in one of the previous
patch series. The primary reason for adding this config was to reduce
the binary size for platforms where it isn’t used. I also think it can
be useful for debugging purposes, such as for identifying regressions.

As for Arm32, it’s not supported at the moment, but I hope support
will be added in the future.

>
> Jan

Best regards,
Mykola