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Re: [Qemu-devel] [PATCH v2] block: Introduce "null" driver
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH v2] block: Introduce "null" driver |
Date: |
Thu, 28 Aug 2014 17:39:47 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Thu, 08/28 10:22, Markus Armbruster wrote:
> Fam Zheng <address@hidden> writes:
>
> > This is an analogue to Linux null_blk. It can be used for testing block
> > device emulation and general block layer functionalities such as
> > coroutines and throttling, where disk IO is not necessary or wanted.
> >
> > Use null:// for AIO version, and null-co:// for coroutine version.
> >
> > Signed-off-by: Fam Zheng <address@hidden>
> >
> > ---
> > V2: Don't #ifdef code, add two drivers. (Benoit)
> > Add to QAPI BlockdevOptions. (Eric)
> > Add "file.size" option to override backend size. (What is a better
> > way to associate /dev/vd{a,b,c} with command line devices, if sizes
> > are the same?)
>
> Is this a request for advice? If yes, please explain the problem in
> more detail, because I'm too dense to get it :)
>
Yes :)
I have more than one virtio-blk:
-drive file=/dev/ram0,id=d0,if=none -device
virtio-blk-pci,drive=d0,x-datap-plane=on \
-drive file=/dev/ram1,id=d0,if=none -device virtio-blk-pci,drive=d1
Then I get /dev/vda and /dev/vdb in guest. They are in the same size.
The question is how do I tell which is /dev/ram0 and which is /dev/ram1,
without bothering peaking PCI addr, etc.?
Fam