On 05/06/12 18:45, Christoffer Dall wrote: > On Mon, May 14, 2012 at 12:26 PM, Marc Zyngier <marc.zyngier at arm.com> wrote: >> On 14/05/12 16:48, Peter Maydell wrote: >>> On 14 May 2012 14:06, Marc Zyngier <marc.zyngier at arm.com> wrote: >>>> This patch series adds support for the architected timer for the >>>> guest. It relies on the VGIC code to inject timer interrupts. >>> >>> This seems like a good point to raise the suggestion that >>> using the in-kernel support for the architected timer and >>> VGIC should be mandatory. >> >> Indeed, thanks for pointing this out. This is why CONFIG_KVM_ARM_TIMER >> depends on KVM_ARM_VGIC && ARM_ARCH_TIMER. >> > is it really that clear that we should just mandate this? If we are > really sure that there will not be devices with virtualization > extensions without GIC virtualization extensions support then fine > (???). Otherwise, I think we definitely want to support such > configurations. There is probably several configurations we want to support: - Cortex-A7/15 host and guest: VGIC + ARCH_TIMER mandatory, or at least be the default configuration. - Hypothetical v7 + virt extensions but without VGIC: QEMU GIC emulation + whatever timer the guest wants to use (and that QEMU provides). Whether or not someone will build this hypothetical v7, I have no idea. But the fact that someone *could* build such a thing means we should keep our interrupt injection code flexible enough. When it comes to the architected timer, it is practically impossible to use it in a guest without VGIC support. Even worse, it is impossible to hide it from the guest. M. -- Jazz is not dead. It just smells funny...
