From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [kvmarm] [RFC PATCH 0/3] KVM: ARM: Get rid of hardcoded VGIC addresses Date: Thu, 25 Oct 2012 18:32:29 +0200 Message-ID: <5089699D.3050004@siemens.com> References: <1350173065-35350-1-git-send-email-c.dall@virtualopensystems.com> <507F172D.2030802@suse.de> <20121017221022.GA4333@bloggs.ozlabs.ibm.com> <1350518331.4678.114.camel@pasglop> <508675FC.7090901@siemens.com> <20121024005017.GA17834@bloggs.ozlabs.ibm.com> <5089656A.9010704@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Paul Mackerras , Christoffer Dall , Benjamin Herrenschmidt , Alexander Graf , "kvmarm@lists.cs.columbia.edu" , "kvm@vger.kernel.org" , kvm-ppc , Peter Maydell To: Paolo Bonzini Return-path: In-Reply-To: <5089656A.9010704@redhat.com> Sender: kvm-ppc-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 2012-10-25 18:14, Paolo Bonzini wrote: > Il 24/10/2012 02:50, Paul Mackerras ha scritto: >> So we could indeed use the existing KVM_CREATE_IRQCHIP to tell KVM to >> create a presentation controller per vcpu. But then how do we tell >> KVM how many source controllers we want and how many interrupts each >> source controller should handle? The source controllers are not tied >> to any particular vcpu, and a source controller could potentially have >> 100s of interrupts or more (particularly with MSIs). Configuration of >> each source fits into 64 bits, so if we tried to use KVM_SET_IRQCHIP >> for configuring a source controller we'd be limited to 64 interrupts >> per source controller. > > As Jan said, there's more than a few similarities between the x86 and > PPC model. > > Taking inspiration from the x86 API, configuring the source controller > seems to be more of a task for KVM_SET_GSI_ROUTING (a very x86-centric > name, I must admit). For wiring things together, I agree. But the IOAPIC has a fixed number of input lines per chip, Power needs to configure them. I don't think deriving this from addressed lines is the best solution. Some lines may be configured (too) late, when the chip should have defined its configuration already. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux