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Re: [PATCH 7/7] gnttab: unreachable code when GNTTAB_MAX_VERSION < 2
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Mykola Kvach <xakep.amatop@xxxxxxxxx>
- Date: Thu, 24 Sep 2026 21:54:45 +0300
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- Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
- Delivery-date: Thu, 24 Sep 2026 18:55:06 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Thu, Sep 24, 2026 at 9:39 PM Mykola Kvach <xakep.amatop@xxxxxxxxx> wrote:
>
> Hi,
>
> On Tue, Jul 28, 2026 at 4:53 PM Jan Beulich <jbeulich@xxxxxxxx> wrote:
> >
> > I'm surprised Eclair doesn't spot the large chunks of unreachable code on
> > Arm, i.e. violations of Misra C:2012 rule 2.1.
> >
> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > ---
> > This pretty certainly isn't dealing with everything. For example, with
> > another helper the gt_version field could likely also become conditional.
> > With some more effort the nr_status_frames field similarly could become
> > conditional.
>
> Could we also skip the gt->status allocation and cleanup on Arm?
> grant_table_init() still allocates this pointer array, although status
> pages are only used by v2. This could be done in a follow-up patch,
> together with the fields you mentioned.
Sorry, I missed that gnttab=max-ver:2 can still enable v2 on Arm.
My suggestion to skip the status allocation would only apply if v2 were
completely disabled on Arm.
~Mykola
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