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Date: Mon, 1 Oct 2012 15:25:06 -0400 (EDT)
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if
 the host supports it
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: kvm <kvm@vger.kernel.org>, Scott Moser <smoser@ubuntu.com>, Jan Kiszka <jan.kiszka@siemens.com>, Marcelo Tosatti <mtosatti@redhat.com>, Michael Tokarev <mjt@tls.msk.ru>, qemu-devel <qemu-devel@nongnu.org>, Bruce Rogers <brogers@suse.com>, Avi Kivity <avi@redhat.com>, Cole Robinson <crobinso@redhat.com>, Andreas =?utf-8?Q?F=C3=A4rber?= <afaerber@suse.de>


> But libguest can set it's accelerator option to whatever it wants.
> 
> If your running QEMU under a VM, it's pretty reasonable to have to
> use a special option IMHO.

It's also reasonable to have consecutive releases change defaults in
a more "friendly" way (i.e. from tcg to kvm:tcg), especially since
we'll get users that formerly used qemu-kvm and never had to specify
neither -machine accel nor --enable-kvm.

> > IMHO, default to KVM, fallback to TCG is the most friendly default
> > behaviour.
> 
> Except if a user expects good network performance and can't
> understand why they're getting 100kb/s.

libguestfs doesn't need network at all (though I wonder if they could
use lxc instead...).

Paolo