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

[Liu, Changpeng]

> -----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.
> 
> Stefan