Dear Jeff,
Jeff Dike wrote:
> On Wed, Sep 12, 2007 at 11:52:32PM +0200, Fermín Galán Márquez wrote:
>> This is the trace (as you can see I're repeated the experiment twice,
>> the result is basically the same), hoping it could be useful to diagnose
>> the problem and fix eventual bugs in the UML kernel. See below regarding
>> the test procedure.
>>
>> (gdb) bt
>> #0 0xb7f9d7f2 in ?? () from /lib/ld-linux.so.2
>> #1 0xb7f19ab0 in tcsetattr () from /lib/i686/cmov/libc.so.6
>> #2 0x080610d5 in generic_console_write (fd=7,
>> buf=0x828fc13 "ip_tables: (C) 2000-2006 Netfilter Core Team\n", n=45)
>> at arch/um/drivers/chan_user.c:37
>> #3 0x0806096e in console_write_chan (chans=0x82756f0,
>> buf=0x828fc13 "ip_tables: (C) 2000-2006 Netfilter Core Team\n", len=45)
>> at arch/um/drivers/chan_kern.c:352
>
> Are you capturing UML output with a script or something? This is the
> signature of the script not reading from the pty, so everything just
> backs up, waiting for the pty to clear up.
AFAIK, no script is capturing (I understand you refers to the output of
the UML linux executable) and, as a matter of fact, I'm getting some
output when execute ./linux. To be precise, this is the exact command
(and the output) I get:
cibeles:/tmp# ./linux ubd0=/tmp/root_fs_debug con=null con0=pts
uml_dir=/tmp umid=run
Core dump limits :
soft - 0
hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:
- /proc/mm...not found: No such file or directory
- PTRACE_FAULTINFO...not found
- PTRACE_LDT...not found
UML running in SKAS0 mode
[no more output, no new prompt]
Then, in a second terminal in the host, I get the pts device and open a
screen in the vm:
cibeles:/tmp# uml_mconsole run/mconsole config con0
Warning: couldn't stat file: /root/.uml/run/mconsole/mconsole - No such
file or directory
Warning: couldn't stat file: /tmp/uml/run/mconsole/mconsole - No such
file or directory
OK pts:/dev/pts/1
cibeles:/tmp# screen /dev/pts/1
[the terminal "goes into" the vm. I use it to cause the fail, as seen below]
Debian GNU/Linux lenny/sid vm tty0
vm login: root
Password:
Last login: Wed Sep 12 23:32:36 2007 on tty0
Linux vm 2.6.22.4-xt-2m #1 Wed Sep 12 20:24:20 CEST 2007 i686
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
vm:~# iptables -L
[no output, linux process reach 100% CPU usage in the host]
In a third host terminal I run gdb:
cibeles:/tmp# cat run/pid
6627
cibeles:/tmp# gdb ./linux 6627
GNU gdb 6.4.90-debian
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...Using host libthread_db
library "/lib/i686/cmov/libthread_db.so.1".
Attaching to program: /tmp/linux, process 6627
Reading symbols from /lib/i686/cmov/libutil.so.1...done.
Loaded symbols for /lib/i686/cmov/libutil.so.1
Reading symbols from /lib/i686/cmov/libc.so.6...done.
Loaded symbols for /lib/i686/cmov/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
0xb7f947f2 in ?? () from /lib/ld-linux.so.2
(gdb) bt
[showing the trace I've already sent in the other mail]
Maybe there are "other outputs" apart of the output that the ./linux
produces which could be causing the problem?
Best regards,
--------------------
Fermín Galán Márquez
CTTC - Centre Tecnològic de Telecomunicacions de Catalunya
Parc Mediterrani de la Tecnologia, Av. del Canal Olímpic s/n, 08860
Castelldefels, Spain
Room 1.02
Tel : +34 93 645 29 12
Fax : +34 93 645 29 01
Email address: fermin dot galan at cttc dot es
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