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Re: [PATCH v2 2/3] arinc653: don't assume Dom0 is the control domain
- To: Jan Beulich <jbeulich@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
- Date: Wed, 25 Mar 2026 17:32:47 -0400
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- Cc: Nathan Studer <nathan.studer@xxxxxxxxxxxxxxx>, Stewart Hildebrand <stewart@xxxxxxx>
- Delivery-date: Wed, 25 Mar 2026 21:33:15 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 3/25/26 08:54, Jan Beulich wrote:
> Leaving aside highly disaggregated environments, the control domain is
> what will invoke XEN_SYSCTL_SCHEDOP_putinfo. Its vCPU-s therefore need to
> be able to run unconditionally, not those of the domain with ID 0 (which
> may not exist at all).
>
> Fixes: 9f0c658baedc ("arinc: add cpu-pool support to scheduler")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> There being no "else" to the if(), what about other control domain vCPU-s?
I wonder if a panic() is appropriate in the else case. If not, at least a
warning or error message should be logged.
> And why are they added to all scheduler instances?
> ---
> v2: New.
>
> --- a/xen/common/sched/arinc653.c
> +++ b/xen/common/sched/arinc653.c
> @@ -411,10 +411,10 @@ a653sched_alloc_udata(const struct sched
> spin_lock_irqsave(&sched_priv->lock, flags);
>
> /*
> - * Add every one of dom0's units to the schedule, as long as there are
> - * slots available.
> + * Add every one of the control domain's units to the schedule, as long
> as
> + * there are slots available.
> */
> - if ( unit->domain->domain_id == 0 )
> + if ( is_control_domain(unit->domain) )
Sorry, I didn't realize before that is_control_domain() includes the idle
domain. We don't want to include the idle domain in the default schedule here.
I suggest adding '&& !is_idle_domain(unit->domain)' or similar.
> {
> entry = sched_priv->num_schedule_entries;
>
>
>
|
