From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 3 Oct 2012 11:02:05 +0100 Subject: [kvmarm] [PATCH v2 08/10] ARM: KVM: VGIC initialisation code In-Reply-To: References: <20121001091244.49503.96318.stgit@ubuntu> <20121001091426.49503.94722.stgit@ubuntu> <20121002092412.GB8847@mudshark.cambridge.arm.com> <20121002192806.GC20411@mudshark.cambridge.arm.com> Message-ID: <20121003100205.GL22445@mudshark.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Oct 02, 2012 at 08:45:54PM +0100, Peter Maydell wrote: > On 2 October 2012 20:28, Will Deacon wrote: > > On Tue, Oct 02, 2012 at 07:31:43PM +0100, Peter Maydell wrote: > >> We probably want to be passing in the "base of the cpu-internal > >> peripherals", rather than "base of the GIC" specifically. For the > >> A15 these are the same thing, but that's not inherent [compare the > >> A9 which has more devices at fixed offsets from a configurable > >> base address]. > > > > If you do that, userspace will need a way to probe the emulated CPU so > > that is knows exactly which set of peripherals there are and which ones it > > needs to emulate. This feels pretty nasty, given that the vgic is handled > > more or less completely by the kernel-side of things. > > Userspace knows what the emulated CPU is because it tells the > kernel which CPU to provide -- the kernel can say "yes" or "no" but > it can't provide a different CPU to the one we ask for, or > one with bits mising... Aha, ok, I didn't realise that's how it works. Does userspace just pass the CPUID or is there an identifier provided by kvm? /me jumps back into the code. Thanks, Will