Re: [Xen-devel] [PATCH v7 16/18] xen: automatically create XenBlockDevice-s

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Kevin Wolf [mailto:kwolf@xxxxxxxxxx]
> Sent: 08 January 2019 12:53
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: Anthony Perard <anthony.perard@xxxxxxxxxx>; qemu-devel@xxxxxxxxxx;
> qemu-block@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx; Max Reitz
> <mreitz@xxxxxxxxxx>; Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Subject: Re: [PATCH v7 16/18] xen: automatically create XenBlockDevice-s
> 
> Am 04.01.2019 um 17:40 hat Paul Durrant geschrieben:
> > > -----Original Message-----
> > > From: Anthony PERARD [mailto:anthony.perard@xxxxxxxxxx]
> > > Sent: 04 January 2019 16:31
> > > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> > > Cc: qemu-devel@xxxxxxxxxx; qemu-block@xxxxxxxxxx; xen-
> > > devel@xxxxxxxxxxxxxxxxxxxx; Kevin Wolf <kwolf@xxxxxxxxxx>; Max Reitz
> > > <mreitz@xxxxxxxxxx>; Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > > Subject: Re: [PATCH v7 16/18] xen: automatically create
> XenBlockDevice-s
> > >
> > > Almost done, there is one thing left which I believe is an issue.
> > > Whenever I attach a raw file to QEMU, it print:
> > >     qemu-system-i386: warning: Opening a block device as a file using
> the
> > > 'file' driver is deprecated
> >
> > Oh, I'd not noticed that... but then I only use raw files occasionally.
> 
> Strictly speaking, this is not about raw (regular) files, but raw block
> devices. 'file' is fine for actual regular files, but the protocol
> driver for block devices is 'host_device'.
> 
> > > raw files should use the "raw" driver, so we aren't done yet.
> >
> > Ok. Having a strictly 2-layer stack actually makes things simpler anyway
> :-)
> 
> Using 'raw' there will make the block layer auto-detect the right
> protocol layer, so this works. If you want to avoid the second layer,
> you'd have to figure out manually whether to use 'file' or
> 'host_device'.

Thanks for the explanation. I'll give it a spin using a device... I've posted 
v8 but, given what you say, I'm still not sure I have it right.

  Paul

> 
> Kevin

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