From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH v4 0/4] virtio: Clean up scatterlists and use the DMA API Date: Tue, 28 Jul 2015 19:19:14 +0200 Message-ID: <55B7B992.8070509@siemens.com> References: <55B73A49.9050206@redhat.com> <1438078345.7562.133.camel@kernel.crashing.org> <55B7799C.3060908@redhat.com> <20150728160358-mutt-send-email-mst@redhat.com> <55B77F8C.7010804@siemens.com> <55B7AF99.2080209@redhat.com> <55B7B105.50200@siemens.com> <55B7B8AF.5060603@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55B7B8AF.5060603@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Archive: List-Post: To: Paolo Bonzini , "Michael S. Tsirkin" Cc: "linux-s390@vger.kernel.org" , xen-devel , Konrad Rzeszutek Wilk , Benjamin Herrenschmidt , Andy Lutomirski , Christian Borntraeger , "linux390@de.ibm.com" , Linux Virtualization List-ID: On 2015-07-28 19:15, Paolo Bonzini wrote: > > > On 28/07/2015 18:42, Jan Kiszka wrote: >>> On the other hand interrupt remapping is absolutely necessary for >>> production use, hence my point that x86 does not promise API stability. >> >> Well, we currently implement the features that the Q35 used to expose. >> Adding interrupt remapping will require a new chipset and/or a hack >> switch to ignore compatibility. > > Isn't the VT-d register space separate from other Q35 features and > backwards-compatible? You could even add it to PIIX in theory just by > adding a DMAR. Yes, it's practically working, but it's not accurate /wrt how that hardware looked like in reality. > > It's not like for example SMRAM, where the registers are in the > northbridge configuration space and move around in every chipset generation. > >>> ("Any kind of stability" actually didn't include crashes; those are not >>> expected :)) >>> >>> The Google patches for userspace PIC and IOAPIC are proceeding well, so >>> hopefully we can have interrupt remapping soon. >> >> If the day had 48 hours... I'd love to look into this, first adding QEMU >> support for the new irqchip architecture. > > I hope I can squeeze in some time for that... Google also had an intern > that was looking at it. Great! Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux