Re: [Xen-devel] xl block-attach vs block-detach

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 01.03.12 at 18:30, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
>> Further, why is it that with no blktap module loaded I'm getting an
>> incomplete attach when using the (deprecated) file:/ format for
>> specifying the backing file? It reports that it would be using qdisk,
>> and blkfront also sees the device appearing, but all I'm seeing in the
>> kernel log is the single message from blkfront's probe function. (With
>> no blktap in pv-ops, I wonder how file backed disks work there.)
>> When trying to detach such a broken device I'm getting
>> "unrecognized disk backend type: 0", and the remove fails.
> 
> That might well be a bug.  In addition to Ian's questions, what do you
> get if you turn on the debug by passing xl lots of -v flags (before
> the block-attach) ?

+ xl -vvvvv block-attach 0 
file:/srv/SuSE/SLES-11-SP1-MINI-ISO-x86_64-GMC3-CD.iso 0xca00 r
libxl: debug: libxl_device.c:183:libxl__device_disk_set_backend: Disk 
vdev=0xca00 spec.backend=unknown
libxl: debug: libxl_device.c:137:disk_try_backend: Disk vdev=0xca00, backend 
phy unsuitable as phys path not a block device
libxl: debug: libxl_device.c:144:disk_try_backend: Disk vdev=0xca00, backend 
tap unsuitable because blktap not available
libxl: debug: libxl_device.c:219:libxl__device_disk_set_backend: Disk 
vdev=0xca00, using backend qdisk
libxl: debug: libxl_device.c:183:libxl__device_disk_set_backend: Disk 
vdev=0xca00 spec.backend=qdisk
xc: debug: hypercall buffer: total allocations:2 total releases:2
xc: debug: hypercall buffer: current allocations:0 maximum allocations:2
xc: debug: hypercall buffer: cache current size:2
xc: debug: hypercall buffer: cache hits:0 misses:2 toobig:0
+ xl -vvvvv block-attach 0 
file:/srv/SuSE/SLES-11-SP1-MINI-ISO-x86_64-GMC3-CD.iso 0xca00 r
libxl: debug: libxl_device.c:183:libxl__device_disk_set_backend: Disk 
vdev=0xca00 spec.backend=unknown
libxl: debug: libxl_device.c:137:disk_try_backend: Disk vdev=0xca00, backend 
phy unsuitable as phys path not a block device
libxl: debug: libxl_device.c:144:disk_try_backend: Disk vdev=0xca00, backend 
tap unsuitable because blktap not available
libxl: debug: libxl_device.c:219:libxl__device_disk_set_backend: Disk 
vdev=0xca00, using backend qdisk
libxl: debug: libxl_device.c:183:libxl__device_disk_set_backend: Disk 
vdev=0xca00 spec.backend=qdisk
xc: debug: hypercall buffer: total allocations:2 total releases:2
xc: debug: hypercall buffer: current allocations:0 maximum allocations:2
xc: debug: hypercall buffer: cache current size:2
xc: debug: hypercall buffer: cache hits:0 misses:2 toobig:0
+ xl -vvvvv block-detach 0 51712
libxl: error: libxl.c:1223:libxl__device_from_disk: unrecognized disk backend 
type: 0

libxl_device_disk_remove failed.
xc: debug: hypercall buffer: total allocations:2 total releases:2
xc: debug: hypercall buffer: current allocations:0 maximum allocations:2
xc: debug: hypercall buffer: cache current size:2
xc: debug: hypercall buffer: cache hits:0 misses:2 toobig:0
+ xl -vvvvv block-detach 0 51712
libxl: error: libxl.c:1223:libxl__device_from_disk: unrecognized disk backend 
type: 0

libxl_device_disk_remove failed.
xc: debug: hypercall buffer: total allocations:2 total releases:2
xc: debug: hypercall buffer: current allocations:0 maximum allocations:2
xc: debug: hypercall buffer: cache current size:2
xc: debug: hypercall buffer: cache hits:0 misses:2 toobig:0

> Can you attach the disk by naming it in the config file ?

Didn't try, for the purpose at hand I want the disk attached to Dom0.

Jan


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