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Re: [Xen-users] How the file-backed VBD works in PV domain?

On 10/01/14 03:36, Younghyun Jo wrote:
> Hello Everyone,
> I'm currently looking into how Xen(PV) Disk I/O works.
> And I want to know how they works in source level.
> As we know, HVM uses QEMU and the PV / PVHVM uses Dom0 backend driver.
> And I could find that the Dom0
> kernel(driver/block/xen-blkback/blkback.c) do disk I/O in LVM-backed VBD.
> But, I want to use File-backed VBD rather than LVM-backed VBD.
> I found that if I use file-backed VBD, then they don't use Dom0 backend
> driver.
> So, Can I use backend driver in file-backed I/O?
> and I want to know how the file-backed VBD works in PV domain.

Everything that's not a block device is handled by Qemu Qdisk, which is
an implementation of blkback in userspace. See hw/block/xen_disk.c in
Qemu upstream source tree for it's implementation.


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