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Re: [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic A
Re: [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic API
Sun, 15 Mar 2009 15:43:13 +0100
On Sun, Mar 15, 2009 at 03:54:26PM +0200, Avi Kivity wrote:
> >Hower the way the new
> >API is designed somewhat gets in the way of my patch series to support
> >Gerd's native preadv/pwritev.
> Can you point out specific issues?
The patch series (now posted) makes all aio APIs use iovecs. The
current non-iovec based SG API would require some nasty shims allocating
nested aiocbs. Or we could just make the sg aio methods fake-ioveced
which is the solution I had before your split, always adding a
one-element iovec to the scsi-generic request structure.
> Using the block layer has the advantage of common setup, statistics, and
> management. I agree that the actual data movement is horribly out of
> sync with the other format drivers.
Yeah, the setup is kinda interwinded with the block layer. I wonder
whether the device-tree ideas will help sorting that out.
Note that I eventually want to support SG_IO on cdrom devices for
burning etc at which point we need to support scsi-generic even
if another driver is attached. Note entirely sure how to handle
[Qemu-devel] [PATCH 3/3] Drop internal bdrv_pread()/bdrv_pwrite() APIs, Avi Kivity, 2009/03/12
[Qemu-devel] [PATCH 2/3] Add internal scsi generic block API, Avi Kivity, 2009/03/12
[Qemu-devel] Re: [PATCH 0/3] Remove ->bdrv_pread() internal block layer API (v2), Anthony Liguori, 2009/03/12