From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Andreas_F=E4rber?= Subject: Re: [PATCH qom-cpu 3/7] target-i386: Disable kvm_mmu by default Date: Thu, 10 Jan 2013 23:40:58 +0100 Message-ID: <50EF437A.10507@suse.de> References: <1357582848-16575-1-git-send-email-ehabkost@redhat.com> <1357582848-16575-4-git-send-email-ehabkost@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Cc: kvm@vger.kernel.org, Gleb Natapov , "Michael S. Tsirkin" , libvir-list@redhat.com, Marcelo Tosatti , qemu-devel@nongnu.org, Igor Mammedov , Jiri Denemark To: Eduardo Habkost Return-path: In-Reply-To: <1357582848-16575-4-git-send-email-ehabkost@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org Am 07.01.2013 19:20, schrieb Eduardo Habkost: > KVM_CAP_PV_MMU capability reporting was removed from the kernel since > v2.6.33 (see commit a68a6a7282373), and was completely removed from the > kernel since v3.3 (see commit fb92045843). It doesn't make sense to kee= p > it enabled by default, as it would cause unnecessary hassle when using > the "enforce" flag. >=20 > This disables kvm_mmu on all machine-types. With this fix, the possible > scenarios when migrating from QEMU <=3D 1.3 to QEMU 1.4 are; >=20 > ------------+------------+---------------------------------------------= ------- > src kernel | dst kernel | Result > ------------+------------+---------------------------------------------= ------- > >=3D 2.6.33 | any | kvm_mmu was already disabled and will stay= disabled > <=3D 2.6.32 | >=3D 3.3 | correct live migration is impossible > <=3D 2.6.32 | <=3D 3.2 | kvm_mmu will be disabled on next guest r= eboot * > ------------+------------+---------------------------------------------= ------- When using ASCII art, please remember to use at most 76 characters, to avoid linewraps in git-log. Shortening the second column fixes this. Andreas >=20 > * If they are running kernel <=3D 2.6.32 and want kvm_mmu to be kept > enabled on guest reboot, they can explicitly add +kvm_mmu to the QEM= U > command-line. Using 2.6.33 and higher, it is not possible to enable > kvm_mmu explicitly anymore. >=20 > Signed-off-by: Eduardo Habkost --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffer; HRB 16746 AG N=FCrnbe= rg