Re: Implementing NVMHCI...

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Mon, 2009-04-13 at 08:10 -0700, Linus Torvalds wrote:
> On Mon, 13 Apr 2009, Avi Kivity wrote:
> > > Of course, the _really_ conclusive thing (in a virtualized environment) is
> > > to just make the virtual disk only able to do 16kB IO accesses (and with
> > > 16kB alignment). IOW, actually emulate a disk with a 16kB hard sector size,
> > > and reporting a 16kB sector size to the READ CAPACITY command. If it works
> > > then, then clearly WNT has no issues with bigger sectors.
> > 
> > I don't think IDE supports this?  And Windows 2008 doesn't like the LSI
> > emulated device we expose.
> 
> Yeah, you'd have to have the OS use the SCSI commands for disk discovery, 
> so at least a SATA interface. With IDE disks, the sector size always has 
> to be 512 bytes, I think.

Actually, the latest ATA rev supports different sector sizes in
preparation for native 4k sector size SATA disks (words 117-118 of
IDENTIFY).  Matthew Wilcox already has the patches for libata ready.

James