On 22.07.2013 11:58, Daniel P. Berrange wrote:
On Fri, Jul 12, 2013 at 05:13:56PM +0200, Viktor Mihajlovski wrote:
The alias for hostdevs of type SCSI can be too long for QEMU if larger LUNs are encountered. Here's a real life example:
<hostdev mode='subsystem' type='scsi' managed='no'> <source> <adapter name='scsi_host0'/> <address bus='0' target='19' unit='1088634913'/> </source> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </hostdev>
this results in a too long drive id, resulting in QEMU yelling
Property 'scsi-generic.drive' can't find value 'drive-hostdev-scsi_host0-0-19-1088634913'
This commit changes the alias back to the default hostdev$(index) scheme.
Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com> ---
Actually this is highlighting a larger issue. Apparently QEMU ids are limited to a length of 32 bytes. This means that SCSI based drives are also in danger to exceed this limit. We should consider to use a drive index for controller-attached disks for alias generation instead of the verbose drive-$bustype-$busaddress schema.
Urgh that sucks. I had no idea QEMU would impose such an arbitrary length limitation for something like this.
src/qemu/qemu_command.c | 10 +--------- .../qemuxml2argv-hostdev-scsi-boot.args | 4 ++-- .../qemuxml2argv-hostdev-scsi-lsi.args | 4 ++-- .../qemuxml2argv-hostdev-scsi-readonly.args | 4 ++-- .../qemuxml2argv-hostdev-scsi-virtio-scsi.args | 4 ++-- 5 files changed, 9 insertions(+), 17 deletions(-)
ACK
There's no back compatibility issues, since we store the aliases for running guests in the state XML. Thus this will only affect newly launched guests
Daniel
Pushed now. Michal