Re: [Xen-users] xm block-attach from dom0 and exception looking up device number for /dev/xvda1 - why ?

["Ian Brown" <ianbrn@xxxxxxxxx>]

Hello,
Sorry. This does not solve my problem.

I tried:

mknod /dev/xvda  b 202 0
mknod /dev/xvda1 b 202 1
xm block-attach 0 tap:aio:/var/lib/xen/images/guest2/guest2File /dev/xvda1 w 0
no errors in xend.log file (the output of xend.log is in the end)

then:

mount /dev/xvda1 /mnt/xvda1/
gives the following error:
mount: /dev/xvda1 is not a valid block device

and mount fails !

cat /proc/devices | grep 202
gives
202 cpu/msr

is the xvd driver missing here ? what should I do ?

the output of xend.log after xm block-attach 0...:
...
[2007-04-15 15:33:31 xend 3123] DEBUG (DevController:110)
DevController: writing {'backend-id': '0', 'virtual-device': '51713',
'device-type': 'disk', 'state': '1', 'backend':
'/local/domain/0/backend/tap/0/51713'} to
/local/domain/0/device/vbd/51713.
[2007-04-15 15:33:31 xend 3123] DEBUG (DevController:112)
DevController: writing {'domain': 'Domain-0', 'frontend':
'/local/domain/0/device/vbd/51713', 'dev': '/dev/xvda1', 'state': '1',
'params': 'aio:/var/lib/xen/images/guest2/guest2File', 'mode': 'w',
'online': '1', 'frontend-id': '0', 'type': 'tap'} to
/local/domain/0/backend/tap/0/51713.
[2007-04-15 15:33:31 xend 3123] DEBUG (DevController:149) Waiting for 51713.
[2007-04-15 15:33:31 xend 3123] DEBUG (DevController:464)
hotplugStatusCallback
/local/domain/0/backend/tap/0/51713/hotplug-status.
[2007-04-15 15:33:31 xend 3123] DEBUG (DevController:464)
hotplugStatusCallback
/local/domain/0/backend/tap/0/51713/hotplug-status.
[2007-04-15 15:33:31 xend 3123] DEBUG (DevController:478)
hotplugStatusCallback 1.
...
...


Any ideas?
Regards,
Ian


On 4/13/07, trilok nuwal <tc.nuwal@xxxxxxxxx> wrote:
> On 4/13/07, Ian Brown <ianbrn@xxxxxxxxx> wrote:
> > Hello,
> > I want to mounting an image in Dom0 using the blktap driver.
> > I of course can access the raw image, but I
> >
> > There is **exactly** such an example in the blktap readme:
>
>   You can try onething,  create /dev/xvda1 using mknod then try this.
>
>
> > xm block-attach 0 tap:aio:<FILENAME> /dev/xvda1 w 0
> > mount /dev/xvda1 /mnt/disk        <--- don't use loop driver
> >
> > see
> http://lxr.xensource.com/lxr/source/tools/blktap/README
> >
> > So I don't understand what am I missing so it can work.
> >
> > Regares,
> > Ian
> >
> > On 4/13/07, trilok nuwal <tc.nuwal@xxxxxxxxx> wrote:
> > >
> > >
> > > On 4/11/07, Ian Brown <ianbrn@xxxxxxxxx> wrote:
> > > > Hello,
> > > >
> > > > I am trying to perform "xm block-attach" from dom0 according to the
> > > > Xen blktap README.
> > > >
> > > > What I am trying to do is :
> > > >
> > > > xm block-attach 0
> > > tap:aio:/var/lib/xen/images/guest2/guest2File
> /dev/xvda1 w
> > > 0
> > >
> > >  I am doubtful if  this works to dom0, this should be used with other
> > > domains. Why u need this device in dom0 . Everything is available to
> dom0.
> > >
> > > > whereas "/var/lib/xen/images/guest2/guest2File" is
> the
> > > image which appears
> > > > in the domU cofig file:
> > > > disk = [
> > > 'tap:aio:/var/lib/xen/images/guest2/guest2File,xvda,w',
> > > ...]
> > > >
> > > > I see the following error message in /var/log/xen/xend.log: (of dom0
> > > > of course)
> > > >
> > > > [2007-04-11 10:51:24 xend 3123] DEBUG (blkif:24) exception
> > > > looking up device number for /dev/xvda1:
> > > > [Errno 2] No such file or directory: '/dev/xvda1'
> > > >
> > > > Indeed, ls -al /dev/xvda1 in dom0 gives:
> > > >   ls: /dev/xvda1: No such file or directory
> > > > and also  running "cat /proc/partitions |grep xvd" from dom0
> > > > gives nothing.
> > > >
> > > >
> > > > I want to add that tring mounting from dom0 onto domU succeeds:
> > > > xm block-attach 1
> > > tap:aio:/var/lib/xen/images/guest2/guest2File
> /dev/xvda1 w
> > > > (where 1 is the number of domU).
> > > > Also mounting /dev/xvda1 from domU succeeds.
> > > >
> > > > Any idea ? what should I do so that it will succeed ? is this readme
> > > > not valid anynmore ??
> > > >
> > > >
> > > > Ian
> > > >
> > > > _______________________________________________
> > > > Xen-users mailing list
> > > > Xen-users@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.xensource.com/xen-users
> > > >
> > >
> > >
> >
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