On Mon, Oct 17, 2011 at 12:27:17PM -0000, Robert Lowery wrote:
> Public bug reported:
>
> I have been using diskless mythbuntu (based on ltsp) for several years.
> After upgrading from 11.04 -> 11.10, nbd mounting has stopped working
> from the front ends.
>
> In /var/log/syslog on the server I get the error "nbd0: Wrong magic
> (0x25609513)".
That's actually a kernel message, not a server message, so presumably
mythbuntu is configured to send syslog messages to the server over the
network?
> nbd-server is configured to use inetd using port 2000.
>
> I have also tried stopping inetd and manually running nbd on the local server
> using the commands
> nbd-server -d 2000 /opt/ltsp/images/i386.img
> and
> nbd-client localhost 2000 /dev/nbd0
>
> This results in the same error.
Does this happen immediately, or does it take a few moments? Do you
perhaps have to read from the device before it happens?
> I have tried turing on debugflags=0xfff in the nbd kernel module and
> building nbd-server with additional tracing but am having trouble
> solving the issue.
>
> grepping the source code 0x25609513 appears to be the correct magic number
> #define NBD_REQUEST_MAGIC 0x25609513, so I'm not sure what going on. Perhaps
> an introduced endianess issue?
No. The 'request' and 'reply' are from the client side. If my
understanding is correct, this would mean you're getting a REQUEST_MAGIC
on a reply packet. That's clearly wrong. Why that's happening, however,
isn't clear to me.
> It is not clear to me if this is a kernel module issue or a nbd package
> issue.
>
> If there is any additional information I can supply, please let me know
Please do the following:
apt-get build-dep nbd
apt-get source nbd
cd nbd-2.9.23
now use your favourite editor to edit the file 'debian/rules'. Near the
top of that file, you'll find the following target:
override_dh_auto_configure: debian/po/templates.pot
test -f nbd.h
dh_auto_configure -- --enable-lfs --enable-syslog \
--prefix=/ --mandir=/usr/share/man
Add a '--enable-debug' parameter:
override_dh_auto_configure: debian/po/templates.pot
test -f nbd.h
dh_auto_configure -- --enable-lfs --enable-syslog \
--prefix=/ --mandir=/usr/share/man --enable-debug
Then rebuild:
dpkg-buildpackage -rfakeroot -uc -us
(note that you need to do this in the 'nbd-2.9.23' directory, *not* in
'nbd-2.9.23/debian').
Finally, install the rebuilt package:
cd ..
sudo dpkg -i nbd-server_2.9.23*deb
This replaces your nbd-server with a version that will not fork, cannot
be used in inetd mode (so you'll have to do the manual mode like you did
earlier), and which will produce a *lot* of debugging output when a
session is running. Please copy-and-paste that output into a followup to
this bugreport.
Once you've done this, you may want to revert to the original
nbd-server:
apt-get --reinstall install nbd-server
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https://bugs.launchpad.net/bugs/876455
Title:
nbd0: Wrong magic (0x25609513) error in Oneiric
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