Hi Kip,

Crash output:
root:04:20 PM:root $ ./gdbserver-xen 127.0.0.1:9999 --attach 2
domain currently paused
Attached; pid = 2
Listening on port 9999
Remote debugging from host 127.0.0.1
Segmentation fault (core dumped)
Normal output:
root:04:23 PM:root $ ./gdbserver-xen 127.0.0.1:9999 --attach 3
domain currently paused
Attached; pid = 3
Listening on port 9999
Remote debugging from host 127.0.0.1
Here's the backtrace from the core file (which I have attached):
Thanks yet again, :-)
-Jon
root:04:25 PM:root $ gdb gdbserver-xen
(gdb) core core
Core was generated by `./gdbserver-xen 127.0.0.1:9999 --attach 2'.
Program terminated with signal 11, Segmentation fault.
warning: current_sos: Can't read pathname for load map: Input/output error
Reading symbols from /usr/lib/libxenctrl.so.3.0...done.
Loaded symbols for /usr/lib/libxenctrl.so.3.0
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
#0 0x40021fb4 in map_domain_va () from /usr/lib/libxenctrl.so.3.0
(gdb) bt
#0 0x40021fb4 in map_domain_va () from /usr/lib/libxenctrl.so.3.0
#1 0x4002268a in xc_ptrace () from /usr/lib/libxenctrl.so.3.0
#2 0x0804cb27 in linux_read_memory (memaddr=0, myaddr=0xbff5ab50 "", len=8)
 at ../../../gdb-6.2.1/gdb/gdbserver/linux-xen-low.c:394

locations, and GDB cannot access its value.
)
 at ../../../gdb-6.2.1/gdb/gdbserver/target.c:64
#4 0x0804b41b in main (argc=4, argv=0xbff5b3a4)
 at ../../../gdb-6.2.1/gdb/gdbserver/server.c:483
Kip Macy wrote:

Jonathan -
gdbserver-xen is behaving as I expect, now that I've turned off

crash_debug in Rules.mk <http://Rules.mk>. Thanks again for your helpful
suggestions.
Indeed, I am interested in debugging domU. However, the domU kernel
I've built is crashing and / or xend is crashing before the domain can
even be started "paused".

Are you passing -p to "xm create"? If so, it is a xend problem, because that
will pause the OS before the *first instruction*. However, it shouldn't be
causing xend to crash until it gets to the xenbus init code.
If I try to use gdbserver-xen to connect to one of my

invisible-to-xm-list domains, gdbserver-xen segfaults once gdb connects
to it. I believe this is interesting because gdbserver-xen will
complain about nonexistant domains if I pass it a domain id which has
never been used this boot cycle. If I pass it a domain which ran
successfully, but has shutdown, it says "getdomaininfo failed". Hence,
I believe the segfault of gdbserver-xen is directly related to the
changes I've made to the kernel I want to debug.

Could you send me the output from the two different runs? Odds are the
segfault is easily fixable.

Attachment: core
Description: Binary data

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature

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