From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:38842) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R0Bwy-0008DE-6r for qemu-devel@nongnu.org; Sun, 04 Sep 2011 08:37:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1R0Bwx-0007qb-0Q for qemu-devel@nongnu.org; Sun, 04 Sep 2011 08:37:24 -0400 Received: from fmmailgate02.web.de ([217.72.192.227]:43362) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R0Bww-0007qS-Lh for qemu-devel@nongnu.org; Sun, 04 Sep 2011 08:37:22 -0400 Message-ID: <4E6370FD.2010703@web.de> Date: Sun, 04 Sep 2011 14:37:17 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <4E58FC3F.6080809@web.de> <4E5BE7C5.60705@us.ibm.com> <4E5BFF51.9010503@web.de> <4E5C00F0.9070103@redhat.com> <4E5D39C8.5020205@web.de> <4E5E1297.3050904@siemens.com> <4E636C72.4080608@redhat.com> In-Reply-To: <4E636C72.4080608@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig61A3C6C22CBA3A68CB4E6CF8" Sender: jan.kiszka@web.de Subject: Re: [Qemu-devel] [PATCH] pc: Clean up PIC-to-APIC IRQ path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Lucas Meneghel Rodrigues , Peter Maydell , Anthony Liguori , Marcelo Tosatti , qemu-devel , Blue Swirl , Gerd Hoffmann This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig61A3C6C22CBA3A68CB4E6CF8 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2011-09-04 14:17, Avi Kivity wrote: > On 08/31/2011 01:53 PM, Jan Kiszka wrote: >> On 2011-08-31 10:25, Peter Maydell wrote: >> > On 30 August 2011 20:28, Jan Kiszka wrote: >> >> Yes, that's the current state. Once we have bidirectional IRQ >> links in >> >> place (pushing downward, querying upward - required to skip IRQ >> routers >> >> for fast, lockless deliveries), that should change again. >> > >> > Can you elaborate a bit more on this? I don't think anybody has >> > proposed links with their own internal state before in the qdev/qom= >> > discussions... >> >> That basic idea is to allow >> >> a) a discovery of the currently active IRQ path from source to sink >> (that would be possible via QOM just using forward links) >> >> b) skip updating the states of IRQ routers in the common case, just >> signaling directly the sink from the source (to allow in-kernel IR= Q >> delivery or to skip taking some device locks). Whenever some route= r >> is queried for its current IRQ line state, it would have to ask th= e >> preceding IRQ source for its state. So we need a backward link. >> >> We haven't thought about how this could be implemented in details yet >> though. Among other things, it heavily depends on the final QOM design= =2E >> >=20 > Looks like a similar path to the memory API. A declarative description= > of the interrupt hierarchy allows routes to be precalculated and flatte= ned. >=20 > (here it's strictly an optimization; with the memory API it's a > requirement since kvm requires a flattened representation, and tcg is > greatly simplified by it). With current kvm device assignment it's mandatory as it only support kernel/kernel IRQ delivery. Only vfio's eventfds will make it optional (but still highly desirable). Jan --------------enig61A3C6C22CBA3A68CB4E6CF8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk5jcP0ACgkQitSsb3rl5xSBPACeK5R9rv1lvNLNshe5VPb3mW0d 80EAoKI6OEe9DJ55H6gKI4yqhQOCpN2O =u4Zj -----END PGP SIGNATURE----- --------------enig61A3C6C22CBA3A68CB4E6CF8--