Re: [Xen-devel] [PATCH 1 of 2] blkfront: sector size > 512

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 21/05/2009 06:20, "Samuel Thibault" <samuel.thibault@xxxxxxxxxxxx> wrote:

>> Yeah, I am surprised as you are, but the linux blkfront does the same
>> thing so I prefer to avoid changing the protocol now.
> 
> Well, it's not about changing the protocol, it's about fixing drivers
> doing the wrong thing according to the documentation.  What is the use
> of the xenstore sector_size value if not here?

It's due to the protocol having evolved a bit. The xenstore sector_size was
added a bit later, specifically after testing on CD-ROM drives, to require
that frontends issue sector_size-aligned and -sized requests. Otherwise
Linux blkdev subsystem was dropping the reqs on the floor. But we did not
change the wire request format at that time.

Yeah, I'd take a patch to add a nice clear comment about this to blkif.h.
;-)

 -- Keir



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