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Re: [Qemu-devel] [PATCH] virtio-scsi: fix "written length" field in the
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] virtio-scsi: fix "written length" field in the used ring |
Date: |
Mon, 27 Apr 2015 16:18:43 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 27/04/2015 16:04, Michael S. Tsirkin wrote:
>> > Because virtio-blk uses a response footer and virtio-scsi uses a
>> > response header, fixing virtio-blk is much harder. You need to add a
>> > new argument to virtqueue_push. I'd really prefer someone else to do it...
>> >
>> > Paolo
> OK but what's the desired API?
> Do you know the host length or might any part of iov
> be dirty?
For a 1-sector request and a 2048+1 bytes iov, I know that I've written
bytes 0-511 and byte 2048.
So I have to dirty all 2049 bytes, but the written length should be 512.
Right now we pass 2049 to virtqueue_push and write 2049 to the written
length, I'd need another argument to pass the 512.
Paolo