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

[Stefan Hajnoczi]

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.

Thanks,
Stefan

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