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Date: Wed, 03 Jun 2009 17:06:49 -0400
From: john cooper <john.cooper@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH 0/2] Add serial number support for
	virtio_blk, V4a
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To: KVM list <kvm@vger.kernel.org>, qemu-devel@nongnu.org
Cc: john.cooper@redhat.com, Rusty Russell <rusty@rustcorp.com.au>, Christoph Hellwig <hch@lst.de>

[Cosmetic changes to prior version, documentation
added to individual patches.]

This patch allows passing of a virtio_blk drive
serial number from qemu into a guest's virtio_blk
driver, and provides a means to access the serial
number from a guest's userspace.

Equivalent functionality currently exists for IDE
and SCSI, however it is not yet implemented for
virtio.  Scenarios exist where guest code relies
on a unique drive serial number to correctly
identify the machine environment in which it
exists.  The following patches, relative to
qemu-kvm.git and 2.6.29.3 respectively, provide
an equivalent mechanism for virtio_blk.

Usage:

With a patched qemu and guest virtio_blk driver,
launch the guest with a virtio_blk drive specifying
a serial number, eg:

    -drive ... ,if=virtio,serial=ThisSpace4Rent, ...

In the guest retrieve via HDIO_GET_IDENTITY ioctl
to the virtio_blk driver, (eg):

    # hdparm -i /dev/vda

hdparm -i /dev/vda

/dev/vda:

 Model=QEMU VIRT_BLK, FwRev=0.10.50, SerialNo=ThisSpace4Rent


-john

-- 
john.cooper@redhat.com