Re: [PATCH RFC] xfs: set block device logical sector size on xfs_buftarg

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

On 11/14/13, 7:37 AM, Christoph Hellwig wrote:
> On Thu, Nov 14, 2013 at 08:26:58AM +1100, Dave Chinner wrote:
>> Seems like that's the avenue for improvement here to me. i.e. expose
>> the correct values to the guest so it's mkfs does the right thing.
>> Or, alternatively, make qemu buffer non-aligned/sized IOs itself
>> internally.
> 
> I've implemented the support to expose these to the guest in qemu
> years ago.  But the problem remains that this is information which
> needs to be attached to the image, which can't really work with raw
> images, and no one has bother to implement the support to store it
> for say qcow2.
> 

Ok but once again - this is not a guest mkfs issue.  The reported
problem is that the guest cannot _boot_ in cache=none mode because
the bios attempts a 512-byte DIO.

Yes, this is all qemu's fault.   We can fight that in the court
of public opinion, I guess.

-Eric