Re: [Qemu-devel] [PATCH] vhost-blk: turn on pre-defined RO feature bit

[Liu, Changpeng]

> -----Original Message-----
> From: Stefan Hajnoczi [mailto:address@hidden
> Sent: Friday, May 25, 2018 6:20 PM
> To: Liu, Changpeng <address@hidden>
> Cc: address@hidden; address@hidden
> Subject: Re: [PATCH] vhost-blk: turn on pre-defined RO feature bit
> 
> On Tue, May 22, 2018 at 02:39:28PM +0000, Liu, Changpeng wrote:
> >
> >
> > > -----Original Message-----
> > > From: Stefan Hajnoczi [mailto:address@hidden
> > > Sent: Tuesday, May 22, 2018 6:11 AM
> > > To: Liu, Changpeng <address@hidden>
> > > Cc: address@hidden; address@hidden
> > > Subject: Re: [PATCH] vhost-blk: turn on pre-defined RO feature bit
> > >
> > > On Sat, May 19, 2018 at 06:20:16AM +0800, Changpeng Liu wrote:
> > > > Read only feature shouldn't be negotiable, because if the
> > > > backend device reported Read only feature supported, QEMU
> > > > host driver shouldn't change backend's RO attribute.
> > >
> > > I don't understand this patch.
> > >
> > > Does it make *all* virtio-blk devices read-only?
> > If the slave target reported RO feature, the disk in OS should be RO, 
> > currently
> > users should specify in QEMU command to enable RO.
> > >
> > > Or is the idea that the vhost-user slave has to clear the read-only bit
> > > if it is a writable device?
> > Exactly.
> 
> Thanks for explaining!
> 
> Please implement the read-only bit in contrib/vhost-user-blk we it can
> be tested.
Sounds good, will add the test together.
> 
> Thanks,
> Stefan