[libvirt] [PATCH v1 19/19] qemu: Allow the specification of a vhost-scsi devno

Michal Privoznik mprivozn at redhat.com
Tue Aug 9 12:13:33 UTC 2016


On 25.07.2016 22:48, Eric Farman wrote:
> In the case of other SCSI host devices, the device that is created
> within the guest will be within the usual SCSI namespace
> (e.g., host:bus:target:lun).  But for vhost-scsi, the actual naming
> structure will come from the host configuration, and will be
> invisible to both QEMU and Libvirt.  So specifying one with an
> <address type='drive' ...> tag (as is often done for virtio-scsi)
> doesn't make sense in this case, as it will be ignored.
> 
> Nevertheless, we need something to identify our vhost-scsi device,
> so for that we'll drop back to the devno mapping that we use for
> other disks.  (This option exists only for vhost-scsi-ccw, but not
> vhost-scsi-pci.  Hrm...)  This becomes <address type='ccw' ...> in
> the case of s390 systems, and puts the device number on the
> resulting QEMU command line.  Thus, existing device number conflict
> detection can be used across other devices that may or may not be
> specified in the guest XML.
> 
> If one is not specified, we need to be sure to allocate one so that
> we can avoid polluting the device numbers with silently-created
> entries.
> 
> Signed-off-by: Eric Farman <farman at linux.vnet.ibm.com>
> Reviewed-by: Bjoern Walk <bwalk at linux.vnet.ibm.com>
> Reviewed-by: Boris Fiuczynski <fiuczy at linux.vnet.ibm.com>
> ---
>  src/conf/domain_conf.c         | 19 +++++++++++++++++--
>  src/qemu/qemu_command.c        |  7 +++++++
>  src/qemu/qemu_domain_address.c | 10 ++++++++++
>  3 files changed, 34 insertions(+), 2 deletions(-)

I don't feel confident enough to review this one. The code looks okay,
but from higher perspective I have no idea what it does. Sorry.

Michal




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