From: "Michael S. Tsirkin" <mst@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Anthony Liguori <aliguori@us.ibm.com>,
kvm@vger.kernel.org,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
qemu-devel <qemu-devel@nongnu.org>,
virtualization@lists.linux-foundation.org
Subject: Re: [Qemu-devel] Using PCI config space to indicate config location
Date: Wed, 10 Oct 2012 13:37:16 +0200 [thread overview]
Message-ID: <20121010113716.GA5737@redhat.com> (raw)
In-Reply-To: <87wqyz6lf8.fsf@rustcorp.com.au>
On Wed, Oct 10, 2012 at 02:14:11PM +1030, Rusty Russell wrote:
> > See above. A guest could happily just use BAR1/BAR2 and completely
> > ignore BAR0 provided that BAR1/BAR2 are present.
>
> But x86 guests want BAR0 because IO space is faster than MMIO. Right?
Or to be a bit more precise, ATM on x86 emulating IO instructions is
faster than MMIO. IIUC this is since you get the address/data in
registers and don't need to decode them.
--
MST
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Anthony Liguori <aliguori@us.ibm.com>,
kvm@vger.kernel.org, qemu-devel <qemu-devel@nongnu.org>,
virtualization@lists.linux-foundation.org,
Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Qemu-devel] Using PCI config space to indicate config location
Date: Wed, 10 Oct 2012 13:37:16 +0200 [thread overview]
Message-ID: <20121010113716.GA5737@redhat.com> (raw)
In-Reply-To: <87wqyz6lf8.fsf@rustcorp.com.au>
On Wed, Oct 10, 2012 at 02:14:11PM +1030, Rusty Russell wrote:
> > See above. A guest could happily just use BAR1/BAR2 and completely
> > ignore BAR0 provided that BAR1/BAR2 are present.
>
> But x86 guests want BAR0 because IO space is faster than MMIO. Right?
Or to be a bit more precise, ATM on x86 emulating IO instructions is
faster than MMIO. IIUC this is since you get the address/data in
registers and don't need to decode them.
--
MST
next prev parent reply other threads:[~2012-10-10 11:37 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-27 0:29 Proposal for virtio standardization Rusty Russell
2012-09-27 0:29 ` [Qemu-devel] " Rusty Russell
2012-09-27 0:29 ` Rusty Russell
2012-10-04 18:49 ` [Qemu-devel] " Anthony Liguori
2012-10-04 18:49 ` Anthony Liguori
2012-10-08 2:21 ` Using PCI config space to indicate config location Rusty Russell
2012-10-08 2:21 ` [Qemu-devel] " Rusty Russell
2012-10-08 13:58 ` Anthony Liguori
2012-10-08 13:58 ` Anthony Liguori
2012-10-08 14:58 ` Gerd Hoffmann
2012-10-08 14:58 ` Gerd Hoffmann
2012-10-08 15:09 ` Anthony Liguori
2012-10-08 15:09 ` Anthony Liguori
2012-10-08 20:13 ` Gerd Hoffmann
2012-10-08 20:13 ` Gerd Hoffmann
2012-10-08 20:55 ` Anthony Liguori
2012-10-08 20:55 ` Anthony Liguori
2012-10-08 23:56 ` Rusty Russell
2012-10-09 1:51 ` Anthony Liguori
2012-10-09 3:16 ` Rusty Russell
2012-10-09 3:16 ` Rusty Russell
2012-10-09 3:16 ` Rusty Russell
2012-10-09 10:17 ` Avi Kivity
2012-10-09 10:17 ` Avi Kivity
2012-10-09 14:03 ` Anthony Liguori
2012-10-09 14:03 ` Anthony Liguori
2012-10-09 13:56 ` Anthony Liguori
2012-10-09 13:56 ` Anthony Liguori
2012-10-10 3:44 ` Rusty Russell
2012-10-10 3:44 ` Rusty Russell
2012-10-10 11:37 ` Michael S. Tsirkin [this message]
2012-10-10 11:37 ` Michael S. Tsirkin
2012-10-09 13:56 ` Anthony Liguori
2012-10-09 21:09 ` Jamie Lokier
2012-10-09 21:09 ` [Qemu-devel] " Jamie Lokier
2012-10-10 3:44 ` Rusty Russell
2012-10-10 3:44 ` Rusty Russell
2012-10-11 0:08 ` Rusty Russell
2012-10-11 0:08 ` Rusty Russell
2012-10-11 0:08 ` Rusty Russell
2012-10-09 21:09 ` Jamie Lokier
2012-10-09 6:33 ` Gerd Hoffmann
2012-10-09 6:33 ` Gerd Hoffmann
2012-10-09 15:26 ` Anthony Liguori
2012-10-09 15:26 ` Anthony Liguori
2012-10-09 20:24 ` Gerd Hoffmann
2012-10-09 20:24 ` Gerd Hoffmann
2012-10-10 2:54 ` Rusty Russell
2012-10-10 2:54 ` Rusty Russell
2012-10-10 13:36 ` Anthony Liguori
2012-10-10 13:41 ` Michael S. Tsirkin
2012-10-10 13:41 ` Michael S. Tsirkin
2012-10-11 0:43 ` Rusty Russell
2012-10-11 0:43 ` Rusty Russell
2012-10-11 0:43 ` [Qemu-devel] " Rusty Russell
2012-10-10 2:54 ` Rusty Russell
2012-10-09 15:26 ` Anthony Liguori
2012-10-10 8:34 ` Michael S. Tsirkin
2012-10-10 8:34 ` Michael S. Tsirkin
2012-10-08 13:58 ` Anthony Liguori
2012-10-10 8:30 ` Michael S. Tsirkin
2012-10-10 8:30 ` [Qemu-devel] " Michael S. Tsirkin
2012-10-11 1:18 ` Rusty Russell
2012-10-11 1:18 ` [Qemu-devel] " Rusty Russell
2012-10-11 10:23 ` Michael S. Tsirkin
2012-10-11 10:23 ` [Qemu-devel] " Michael S. Tsirkin
2012-10-11 22:29 ` Rusty Russell
2012-10-11 22:29 ` [Qemu-devel] " Rusty Russell
2012-10-12 9:33 ` Michael S. Tsirkin
2012-10-12 9:33 ` [Qemu-devel] " Michael S. Tsirkin
2012-10-12 9:51 ` Rusty Russell
2012-10-12 9:51 ` [Qemu-devel] " Rusty Russell
2012-10-12 10:02 ` Michael S. Tsirkin
2012-10-12 10:02 ` [Qemu-devel] " Michael S. Tsirkin
2012-10-16 13:15 ` Rusty Russell
2012-10-16 13:15 ` [Qemu-devel] " Rusty Russell
2012-10-16 13:30 ` Michael S. Tsirkin
2012-10-16 13:30 ` [Qemu-devel] " Michael S. Tsirkin
2012-10-16 13:52 ` Rusty Russell
2012-10-16 13:52 ` [Qemu-devel] " Rusty Russell
2012-10-16 13:52 ` Rusty Russell
2012-10-16 13:15 ` Rusty Russell
2012-10-11 22:29 ` Rusty Russell
2012-10-08 2:21 ` Rusty Russell
2012-10-04 18:49 ` [Qemu-devel] Proposal for virtio standardization Anthony Liguori
2012-10-09 14:02 ` Cornelia Huck
2012-10-09 14:02 ` [Qemu-devel] " Cornelia Huck
2012-10-10 3:46 ` Rusty Russell
2012-10-10 3:46 ` [Qemu-devel] " Rusty Russell
2012-10-10 3:46 ` Rusty Russell
2012-10-09 14:02 ` Cornelia Huck
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