Re: Block protocol incompatibilities with 4K logical sector size disks

["Roger Pau Monné" <roger.pau@citrix.com>]

On Mon, Sep 02, 2024 at 03:50:17PM +0100, Mark Syms wrote:
> On Mon, 2 Sept 2024 at 09:55, Roger Pau Monné <roger.pau@citrix.com> wrote:
> >
> > > So yes, after more research, having sector in the protocol been a
> > > 512-byte size seems the least bad option. "sector_number" and
> > > "{first,last}_sect" have been described as is for a long while. Only
> > > "sectors" for the size has been described as a "sector-size" quantity.
> >
> > Thanks for your input.  I would also like to hear from the blktap and
> > Windows PV drivers maintainers, as the change that I'm proposing here
> > will require changes to their implementations.
> 
> Well, that's a whole big mess isn't it ;( FWIW, it's tacitly assumed
> that tapdisk is only running on 512 or 512e storage as its primary use
> case is VHD and that driver explodes spectacularly on 4KN. So,
> hardening those implicit conditions into hard explicit ones seems like
> an entirely reasonable thing.

OK, so I take you are fine with the adjustments to the protocol being
suggested here, and will be happy to adjust blktap if/when required to
meet them (if it ever supports exposing 4K sector sized disks).

Thanks for the feedback, will Cc you on the patch to blkif.h for one
extra review if possible.

Roger.