Re: [Xen-devel] bug when using 4K sectors?

[James Harper <james.harper@xxxxxxxxxxxxxxxx>]

> > So a sector-size of 4096 would basically be a 512e device, allowing
> > the underlying OS to communicate in 512 byte blocks but knowing that
> > things will work best in 4096 byte sized transfers aligned to
> > multiples of 4096 bytes, right?
> 
> My recollection is that blkfront is required to submit only appropriately 
> -sized
> and -aligned requests; i.e. it's not merely advisory. I remember this got
> added for CD-ROM support and if they had worked without this, I'm sure we
> wouldn't have bothered!
> 

That's a shame. It would be good to have separate values for Physical and 
Logical block sizes so the guest VM can make appropriate alignment decisions. 
In fact there is a lot of stuff in /sys for the block devices that would be 
nice to be mapped into xenstore!

James

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