From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:52211) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QyTyv-00084R-IX for qemu-devel@nongnu.org; Tue, 30 Aug 2011 15:28:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QyTyu-0008UD-Bd for qemu-devel@nongnu.org; Tue, 30 Aug 2011 15:28:21 -0400 Received: from fmmailgate03.web.de ([217.72.192.234]:59415) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QyTyu-0008Sl-0R for qemu-devel@nongnu.org; Tue, 30 Aug 2011 15:28:20 -0400 Message-ID: <4E5D39C8.5020205@web.de> Date: Tue, 30 Aug 2011 21:28:08 +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> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig01439EBC39C0657D6E157319" 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: Blue Swirl Cc: Lucas Meneghel Rodrigues , Anthony Liguori , Marcelo Tosatti , qemu-devel , Avi Kivity , Gerd Hoffmann This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig01439EBC39C0657D6E157319 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2011-08-30 21:19, Blue Swirl wrote: > On Mon, Aug 29, 2011 at 9:13 PM, Avi Kivity wrote: >> On 08/30/2011 12:06 AM, Jan Kiszka wrote: >>> >>>> >>>> Does this need to be save/restored for migration? >>> >>> Nope, but we need some other measure. I thought to remember the pic w= as >>> refreshing this after load, but I do not find any traces of this now.= We >>> likely need a post_load handler in the i8259 that re-asserts the IRQ = as >>> required. >>> >> >> We need some kind of two phase restore. In the first phase all state i= s >> restored; since some of that state drivers outputs that are input to o= ther >> devices, they may experience an edge, and we need to supress that. In= the >> second phase edge detection is unsupressed and the device goes live. >=20 > No. Devices may not perform any externally visible activities (like > toggle a qemu_irq) during or after load because 1) qemu_irq is > stateless and 2) since the receiving end is also freshly loaded, both > states are already in synch without any calls or toggling. 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. For now, that's what I realized in the meantime as well, we can't help saving pic_level in the APIC state. What is the state of substates in pre-1.0? Do we try to use those again in favor of simple field additions under a new state version? Jan --------------enig01439EBC39C0657D6E157319 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/ iEYEARECAAYFAk5dOcgACgkQitSsb3rl5xQENwCeINHUbGJWA4NqsTJg9QG9V2rE SwMAn2tJgyQtZe+/ZJwQhZLmF6AsE3ZP =fs31 -----END PGP SIGNATURE----- --------------enig01439EBC39C0657D6E157319--