From: Stefan Hajnoczi <stefanha@gmail.com>
To: Wei Liu <liuw@liuw.name>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Question on virtio disk maximum index and maximum partition
Date: Wed, 1 Jun 2011 05:56:02 +0100 [thread overview]
Message-ID: <BANLkTimS=6JENjQc0+uBLyB8h2OGiRvA0Q@mail.gmail.com> (raw)
In-Reply-To: <BANLkTik336+xkExg66u7oTQzat49QRz-5Q@mail.gmail.com>
On Wed, Jun 1, 2011 at 2:06 AM, Wei Liu <liuw@liuw.name> wrote:
> I'm programming for virtio disk support in Xen tool stack. I would
> like to know the limitation of virtio disk.
I'm interested what you are implementing - a virtio-blk backend for
Xen (which would basically mean vhost-blk)?
> That is, what's the maximum number of disks supported through virtio
> bus, and what's the maximum number of partitions supported per disk.
virtio-blk as used by KVM is exposed as a virtio PCI adapter. There
is a 1:1 mapping between virtio-blk, PCI adapters, and block devices
being presented by QEMU:
1 virtio-blk device in guest == 1 virtio-pci adapter in guest == 1
block device in QEMU
The maximum number is really limited by the PCI bus, not virtio. In
terms of coding, you should try not to impose a hard limit at all.
Partitions are not at the virtio-blk level. The guest operating
system will see the virtio-blk disk and scan its partition table to
determine which partitions are available. The limit then depends on
the partitioning scheme that you use (legacy boot record, GPT, etc).
> If I'm posting to the wrong list, please point me the right direction.
You might also be interested in
<virtualization@lists.linux-foundation.org> for general virtio
discussion.
Stefan
next prev parent reply other threads:[~2011-06-01 4:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-01 1:06 [Qemu-devel] Question on virtio disk maximum index and maximum partition Wei Liu
2011-06-01 4:56 ` Stefan Hajnoczi [this message]
2011-06-01 6:03 ` Wei Liu
2011-06-01 10:12 ` Stefano Stabellini
2011-06-14 12:27 ` Richard W.M. Jones
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