Re: [Qemu-devel] [PULL 25/26] block: Remove deprecated -drive option serial

[Kevin Wolf <kwolf@redhat.com>]

Am 22.06.2018 um 17:40 hat Daniel P. Berrangé geschrieben:
> On Fri, Jun 22, 2018 at 04:25:13PM +0200, Kevin Wolf wrote:
> > This was in fact one release longer than our deprecation policy says.
> > Are we serious about the deprecation policy or aren't we?
> > 
> > I might consider reverting a change if it turned out that this requires
> > some massive work in libvirt. But I think this one should be rather easy
> > to fix in libvirt until 3.0 is released.
> 
> I've got a patch mostly ready that converts libvirt to setting these things
> on the frontend device, however, I've got some queries...
> 
>  - usb-storage  - doesn't appear to support geometry or werror/rerror
> 
>    Will we loose functionality by stopping use of -drive for werror
> 
>    Loosing geometry feels relevant too, unless it was already ignored
>    when set opf -drive ?

You're right, usb-storage doesn't allow using -device to specify these,
and it does use the values from -drive.

For werror/rerror, we should clearly implement the option forwarding to
scsi-disk so that you can make use of it.

I'm not sure how sane specifying a non-standard CHS geometry for a USB
stick actually is. As an additional difficulty, usb-storage internally
creates a scsi-disk device (not scsi-hd), which is also considered
legacy and doesn't support the geometry options either, so it's not just
simple forwarding. We removed an actual feature there, but that feature
was probably never intended nor used.

If someone comes up with a compelling reason why they really need to
configure the CHS geometry of their USB sticks, I guess we can do it. My
real USB sticks I tested don't even support MODE_PAGE_HD_GEOMETRY
(though they have MODE_PAGE_FLEXIBLE_DISK_GEOMETRY).

>  - SD card - requires -drive with if=sd, no -device support AFAICT
> 
>    Will we loose functionality be stopping use of -drive for if=sd, or
>    is this stuff ignored anyway ?

This was already silently ignored.

>  - ide-cd/scsi-id - doesn't support geometry
> 
>    Presumably becuase its irrelevant for CDs

Yes, geometry has no effect for CDs.

Kevin