From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Anthony PERARD <anthony.perard@citrix.com>,
Xen Devel <xen-devel@lists.xen.org>,
QEMU-devel <qemu-devel@nongnu.org>,
Anthony Liguori <anthony@codemonkey.ws>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [Qemu-devel] [PATCH 4/4] xen: Fix PV-on-HVM
Date: Wed, 16 May 2012 10:42:56 +0200 [thread overview]
Message-ID: <4FB36890.3090301@redhat.com> (raw)
In-Reply-To: <20120516081341.GB3183@redhat.com>
Il 16/05/2012 10:13, Michael S. Tsirkin ha scritto:
> On Wed, May 16, 2012 at 10:06:25AM +0200, Paolo Bonzini wrote:
>> On Xen the PV drivers can ask the firmware to surprise-remove the
>> emulated NICs.
>
> So driver tells firmware (meaning acpi? how?) that it's ok
> to do surprize removal?
It writes something to some I/O port, and then QEMU surprise-removes the
NICs.
>> Of course it has to do it early enough so that the guest
>> doesn't crash.
>
> What does early enough mean and how do we ensure that?
Early enough means that the I/O port is written very early in the boot
process, even before the PCI bus is scanned by the OS.
You don't ensure it, it's up to the OS. The OS knows whether its
drivers can cope properly with surprise removal. If they can, in
principle it could write the magic value whenever it wants to.
Paolo
next prev parent reply other threads:[~2012-05-16 8:43 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-15 15:26 [Qemu-devel] [PATCH 1.1 0/4] Xen: Fix PV-on-HVM Anthony PERARD
2012-05-15 15:26 ` [Qemu-devel] [PATCH 1/4] Introduce a new hotplug state: Force eject Anthony PERARD
2012-05-15 18:19 ` Stefano Stabellini
2012-05-15 18:25 ` Anthony PERARD
2012-05-15 20:52 ` Michael S. Tsirkin
2012-05-16 10:32 ` Stefano Stabellini
2012-05-16 11:15 ` Anthony PERARD
2012-05-16 11:23 ` Paolo Bonzini
2012-05-16 11:37 ` Anthony PERARD
2012-05-16 13:20 ` Michael S. Tsirkin
2012-05-16 15:52 ` Paolo Bonzini
2012-05-16 16:25 ` Michael S. Tsirkin
2012-05-16 16:02 ` Anthony Liguori
2012-05-16 16:24 ` Michael S. Tsirkin
2012-05-15 15:26 ` [Qemu-devel] [PATCH 2/4] qdev: Introduce qdev_force_unplug Anthony PERARD
2012-05-15 18:15 ` Stefano Stabellini
2012-05-15 18:22 ` Anthony PERARD
2012-05-15 15:26 ` [Qemu-devel] [PATCH 3/4] pci: Add force_unplug callback Anthony PERARD
2012-05-15 15:26 ` [Qemu-devel] [PATCH 4/4] xen: Fix PV-on-HVM Anthony PERARD
2012-05-15 21:00 ` Michael S. Tsirkin
2012-05-16 8:06 ` Paolo Bonzini
2012-05-16 8:13 ` Michael S. Tsirkin
2012-05-16 8:42 ` Paolo Bonzini [this message]
2012-05-16 10:19 ` Stefano Stabellini
2012-05-16 10:30 ` Michael S. Tsirkin
2012-05-16 10:37 ` Stefano Stabellini
2012-05-16 13:24 ` Michael S. Tsirkin
2012-05-15 16:26 ` [Qemu-devel] [PATCH 1.1 0/4] Xen: " Anthony Liguori
2012-05-15 16:42 ` Stefano Stabellini
2012-05-15 18:20 ` Stefano Stabellini
2012-05-15 21:06 ` Michael S. Tsirkin
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