Re: [PATCH] vhost-blk: Add vhost-blk support v2

On 10/23/2012 08:07 AM, Rusty Russell wrote:

"Michael S. Tsirkin" [off-list ref] writes:

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On Thu, Oct 18, 2012 at 02:50:56PM +1030, Rusty Russell wrote:

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Asias He [off-list ref] writes:

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+#define BLK_HDR	0

What's this for, exactly? Please add a comment.

The block headr is in the first and separate buffer.

Please don't assume this!  We're trying to fix all the assumptions in
qemu at the moment.

vhost_net handles this correctly, taking bytes off the descriptor chain
as required.

Thanks,
Rusty.

BTW are we agreed on the spec update that makes cmd 32 bytes?

vhost-blk doesn't handle scsi requests, does it?

No, it doesn't handle scsi requests currently.

But since we're forced to use a feature bit, we could just put the cmd
size in explicitly.  Though Paulo seems convinced that 32 is always
sufficient.  Whoever implements it gets to decide...

Here's my TODO list:
1) Create qemu helpers to efficiently handle iovecs.
2) Switch all the qemu devices to use them.
3) ... except a special hack for virtio-blk in old-layout mode.
4) Implement pci capability layout RFC for qemu.
   - Detect whether guest uses capabilities.
   - Device config in new mode is le.
   - Add strict checking mode for extra compliance checks?
5) Add explicit size-based accessors to virtio_config in kernel.
6) Update pci capability RFC patches for linux to match.
   - Use explicit accessors to allow for endian conversion.
6) Push virtio torture patch to test variable boundaries.
7) Update spec.

That should keep me amused for a while...

Cheers,
Rusty.

-- 
Asias