From mboxrd@z Thu Jan 1 00:00:00 1970
From: Pavel Fedin
Subject: RE: [PATCH 2/2] Detect vGIC presence at runtime
Date: Thu, 09 Jul 2015 15:50:49 +0300
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Hello!
> why not report ENXIO as an error? If probing the vgic fails due to
> being unable to request the irq or something similar, then surely your
> system has and error and this should be reported.
It is reported by probe function itself.
-ENODEV here means there's no GIC at all. -ENXIO happens when, for example, there is GIC node in
the device tree, but it does not specify vGIC resources. Normally this means that vGIC is defunct on
the machine.
> This may be more nicely implemented by letting the vgic init/probe
> functions set the vgic_present, or maybe better yet, just export a
> function from vgic.c:
>
> bool kvm_vgic_present(void)
> {
> return vgic_ops != NULL;
> }
Is it necessary? Actually this flag is not needed anywhere else except arch/arm/kvm/arm.c, only at
init time. Runtime should, i believe, use irqchip_in_kernel(), because userland can choose just not
to use vGIC for some reason (testing for example).
Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia