[Xen-devel] non-dom0 disk backend still not working after recent patches

[Eric Shelton <eshelton@xxxxxxxxx>]

Although some patches were submitted recently to allow a disk backend
domain to be
specified, it appears there is still some code that presumes dom0 is
the backend.  Has
this actually been tested for creating an HVM?  I am hoping someone a
bit more familiar
with the process of creating an HVM can lend a hand.

As an example, I have a FreeBSD-based domU (9.1 HVM w/ PV drivers,
domid=1, name=freebsd)
on which I created a small 40MB test image at /pool1/media/betest.img,
to see if I could
get another domU to access the image.

After applying the patch I sent out a little earlier today and the
following xl.cfg line
(the below config for hda is my best guess - should this be specified
differently?):

disk = [ 'backend=freebsd, format=raw, vdev=hda,
target=/pool1/media/betest.img, access=rw',
         '/mnt/bootimgs/install-amd64-minimal-20130110.iso,,hdc:cdrom,r' ]

I attempt to start up an HVM, but qemu terminates early.  The HVM
starts up fine if the
hda info is removed.  In the below excerpt from "xl -vvv create ...",
it looks like qemu
is not informed that hda is on domain 1, not dom0.  I assume the
backend domid should be
specified on the command line (unless qemu pulls disk info from
xenstore, in which case
why bother passing any disk parameters via the command line?)

. . .
libxl: debug: libxl_dm.c:1211:libxl__spawn_local_dm: Spawning
device-model /usr/lib/xen/bin/qemu-system-i386 with arguments:
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
/usr/lib/xen/bin/qemu-system-i386
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -xen-domid
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   4
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -chardev
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
socket,id=libxl-cmd,path=/var/run/xen/qmp-libxl-4,server,nowait
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -mon
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
chardev=libxl-cmd,mode=control
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -name
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   gentoo
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -vnc
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   192.168.1.10:1,to=99
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -global
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   isa-fdc.driveA=
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -vga
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   cirrus
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -global
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   vga.vram_size_mb=8
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -boot
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   order=d
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -smp
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   2,maxcpus=2
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -device
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
e1000,id=nic0,netdev=net0,mac=00:16:3e:4c:ff:31
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -netdev
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
type=tap,id=net0,ifname=vif4.0-emu,script=no,downscript=no
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -M
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   xenfv
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -m
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   2040
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -drive
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
file=/pool1/media/betest.img,if=ide,index=0,media=disk,format=raw,cache=writeback
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:   -drive
libxl: debug: libxl_dm.c:1213:libxl__spawn_local_dm:
file=/mnt/bootimgs/install-amd64-minimal-20130110.iso,if=ide,index=2,media=cdrom,format=raw,cache=writeback,id=ide-5632
libxl: debug: libxl_event.c:559:libxl__ev_xswatch_register: watch
w=0xac5240 wpath=/local/domain/0/device-model/4/state token=3/0:
register slotnum=3
libxl: debug: libxl_create.c:1259:do_domain_create: ao 0xac3ba0:
inprogress: poller=0xac4ca0, flags=i
libxl: debug: libxl_event.c:503:watchfd_callback: watch w=0xac5240
wpath=/local/domain/0/device-model/4/state token=3/0: event
epath=/local/domain/0/device-model/4/state
libxl: debug: libxl_event.c:596:libxl__ev_xswatch_deregister: watch
w=0xac5240 wpath=/local/domain/0/device-model/4/state token=3/0:
deregister slotnum=3
libxl: error: libxl_dm.c:1280:device_model_spawn_outcome: domain 4
device model: spawn failed (rc=-3)
libxl: error: libxl_create.c:1091:domcreate_devmodel_started: device
model did not start: -3
libxl: error: libxl_dm.c:1311:libxl__destroy_device_model: Device
Model already exited
libxl: debug: libxl_event.c:1569:libxl__ao_complete: ao 0xac3ba0:
complete, rc=-3
libxl: debug: libxl_event.c:1541:libxl__ao__destroy: ao 0xac3ba0: destroy

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