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

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

On Mon, Sep 02, 2024 at 03:19:56PM +0100, Paul Durrant wrote:
> On 02/09/2024 09:55, Roger Pau Monné wrote:
> [snip]
> > 
> > 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.
> > 
> 
> So IIUC you are proposing to refuse to connect to a frontend that sets
> feature-large-sector-size if sector-size != 512? Is that right?

Is is worth retrofitting this into existing backends?  My suggestion
would be to make `feature-large-sector-size` not mandatory to expose a
sector-size != 512, but I wouldn't go as far as refusing to connect to
frontends that expose the feature.  I have no idea which frontends
might expose `feature-large-sector-size` but still be compatible with
Linux blkback regarding sector-size != 512 (I know the Windows one
isn't).

I think we have reached consensus with Anthony on the approach, so it
might be best if I just draft a proposal change to blkif.h because
that's less ambiguous than attempting to describe it here.

Thanks, Roger.