From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:46733) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RXCLL-0000HA-BJ for qemu-devel@nongnu.org; Sun, 04 Dec 2011 08:43:00 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RXCLK-0001Ip-29 for qemu-devel@nongnu.org; Sun, 04 Dec 2011 08:42:59 -0500 Received: from fmmailgate03.web.de ([217.72.192.234]:59965) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RXCLJ-0001Ib-MU for qemu-devel@nongnu.org; Sun, 04 Dec 2011 08:42:57 -0500 Received: from moweb002.kundenserver.de (moweb002.kundenserver.de [172.19.20.108]) by fmmailgate03.web.de (Postfix) with ESMTP id 5FFB51AB34938 for ; Sun, 4 Dec 2011 14:42:56 +0100 (CET) Message-ID: <4EDB78DE.6000109@web.de> Date: Sun, 04 Dec 2011 14:42:54 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <4EDB762C.7090909@redhat.com> In-Reply-To: <4EDB762C.7090909@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig341FFFFB44E0B5DCB43487CF" Subject: Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Anthony Liguori , kvm@vger.kernel.org, "Michael S. Tsirkin" , Marcelo Tosatti , qemu-devel , Blue Swirl This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig341FFFFB44E0B5DCB43487CF Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2011-12-04 14:31, Avi Kivity wrote: > On 12/03/2011 01:17 PM, Jan Kiszka wrote: >> From: Jan Kiszka >> >> Introduce the alternative 'kvm-i8259' device model that exploits KVM >> in-kernel acceleration. >> >> The PIIX3 initialization code is furthermore extended by KVM specific >> IRQ route setup. Moreover, GSI injection differs in KVM mode from the >> user space model. As we can dispatch ISA-range IRQs to both IOAPIC and= >> PIC inside the kernel, we do not need to inject them separately. This = is >> reflected by a KVM-specific GSI handler. >> >> + >> +qemu_irq *kvm_i8259_init(void) >> +{ >> + ISADevice *dev; >> + >> + dev =3D isa_create("kvm-i8259"); >> >=20 > Same issue. Is this a different device, or an different implementation= > of the same device? They are theoretically the same from guest perspective (therefore you can migrate between machines that differ in this). >=20 > We're forcing migration from 1.0 to 1.1 to disable in-kernel irqchip on= > the target. For qemu itself, that's no issue. But for qemu-kvm, it > will result in loss of performance, or hacks to alias the two back toge= ther. We should this happen with qemu-kvm? The vmstates are compatible, thus you can migration from old qemu-kvm in-kernel devices to the new kvm-* ones (once they are feature-equivalent). Not sure how much hacks this may require to qemu-kvm, but I don't think it should make the situation worse for that tree. Jan --------------enig341FFFFB44E0B5DCB43487CF 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/ iEYEARECAAYFAk7beN4ACgkQitSsb3rl5xTkZwCfVfqmKNU/+V7vbWCio5p3NYTC 7PUAoMiLQCzLCmJa6nGvA5WK7pCaVEmF =PLmZ -----END PGP SIGNATURE----- --------------enig341FFFFB44E0B5DCB43487CF--