From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: RE: Dynamic-irq's in HVM domains Date: Fri, 30 Nov 2007 08:19:54 +0000 Message-ID: <1196410794.14204.18.camel@localhost.localdomain> References: Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: James Harper Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org [Inverting your top-post] > > 'cat /proc/interrupts' in a Linux PV domain shows interrupts starting > > at 256 and labelled as 'Dynamic-irq'. Are these available in a HVM > > domain eg under Windows? On Fri, 2007-11-30 at 13:29 +1100, James Harper wrote: > I'm really desperate for an answer to this question... Dynamic IRQs are just a convenient Linux interface used to represent event channels in order that they can be used with the regular IRQ subsystem. Although I think they were added by Xen folk I don't think there's anything Xen specific or special about them. Event channels are (of course) exposed to HVM guests. The Linux PV-on-HVM drivers export them itself via their own parallel interrupt-like subsystem because not all the native versions supported by the PV-on-HVM drivers have dynamic IRQs. See evtchn_interrupt() and the other code in unmodified_drivers/linux-2.6/platform-pci/evtchn.c Perhaps Windows has a similar concept to dynamic IRQs in its IRQ subsystem, I'm afraid not being a Windows type I have no idea about that. You can still use event channels outside of the regular windows IRQ subsystem though, as demonstrated above. > Failing that, can I use physical IRQ's in a HVM domain to bind to? Eg > nothing is using IRQ 26, can I use that with bind_pirq? The only docs I > can find says 'Furthermore the calling domain must be sufficiently > privileged.', but I'm not sure how privileged 'sufficiently' means in > this context. I doubt that will work, I expect privileged means either domain 0 or a domain with a PCI passthrough device attached... Ian.