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<TITLE>The Answer Guy 51: Console Goes Comatose After a Few Days</TITLE>
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<H4>"The Linux Gazette...<I>making Linux just a little more fun!</I>"</H4>
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<H4>By James T. Dennis,
<a href="mailto:linux-questions-only@ssc.com">linux-questions-only@ssc.com</a><BR>
LinuxCare,
<A HREF="http://www.linuxcare.com/">http://www.linuxcare.com/</A>
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<H3 align="left"><img src="../../gx/dennis/qbubble.gif"
height="50" width="60" alt="(?) " border="0"
>Console Goes Comatose After a Few Days</H3>
<p><strong>From kodancha on Sun, 30 Jan 2000
</strong></p>
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Console Goes Comatose After a Few Days
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<P><STRONG>
sir
</STRONG></P>
<P><STRONG>
i have installed redhat linux 6.1 on piii hardware with fire
walls.IT works fine.But every 3-4 days i have to reboot the system
because of the following.
</STRONG></P>
<P><STRONG>
Sytems will not take any command.When i type any thing cursor
moves but no char appears on the screen.Even cntrl-alt-del is also
not working.But all oher clients connected this server has got no
problem.I tryied stty sane ,cntrl -c etc but it is not
respondig.Can u help me
</STRONG></P>
<P><STRONG>
gjkodancha
</STRONG></P>
<BLOCKQUOTE><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
Well, you description doesn't give me much to go on.
</BLOCKQUOTE>
<BLOCKQUOTE>
Is this in X? Are you using a kernel with frame buffer
(graphics driven text mode) console support?
</BLOCKQUOTE>
<BLOCKQUOTE>
Try building a new kernel. Leave the system in
text mode and disable any "VESA VGA Graphics" support
in the kernel (in menuconfig under the "Console Drivers"
menu). Be sure to enable the "Magic SysRq Key" under
"Kernel Hacking." Read the docs about this "Magic SysRq"
in the <TT>/usr/src/linux/Documentation/sysrq.txt</TT> file.
</BLOCKQUOTE>
<BLOCKQUOTE>
Now, after you've built and installed the new kernel,
when you reboot with it, use runlevel 3 (<A HREF="http://www.redhat.com/">Red Hat</A>:
text mode multi-user mode) rather than runlevel 5
(multi-user with GUI/xdm login mode).
</BLOCKQUOTE>
<BLOCKQUOTE>
If the console seems to go comatose again, try
using some of the Magic SysRq keys, particularly
the p (processor status), t (task list) and m (memory
status) diagnostics, and the k and r keys to kill
everything on a given console and to "reset" the
keyboard driver.
</BLOCKQUOTE>
<BLOCKQUOTE>
A couple of other things you can do:
</BLOCKQUOTE>
<BLOCKQUOTE>
Edit <TT>/etc/syslog.conf</TT> and add a line like:
</BLOCKQUOTE>
<BLOCKQUOTE><BlockQuote><Code>
*.* <TT>/dev/tty12</TT>
</Code></BlockQuote></BLOCKQUOTE>
<BLOCKQUOTE>
... (and restart your syslog daemon). This will
copy all syslog messages to your twelfth virtual
console. When you leave your system unattended,
switch to that VC. If it appears comatose when
you get back, look at the messages at the end.
</BLOCKQUOTE>
<BLOCKQUOTE>
When you restart your system, look at the tail
of the <TT>/var/log/messages</TT> file. That's where most
system warnings and errors are logged.
</BLOCKQUOTE>
<BLOCKQUOTE>
Also you can try logging in via ssh (or telnet,
rlogin or some other insecure protocol) and using
the commands: chvt 1 or chvt 2
... to force the console to switch to another VC.
See if that works.
</BLOCKQUOTE>
<BLOCKQUOTE>
You can also run commands like
</BLOCKQUOTE>
<BLOCKQUOTE><BlockQuote><Code>
stty sane &lt; <TT>/dev/tty1</TT>
</Code></BlockQuote></BLOCKQUOTE>
<BLOCKQUOTE>
And:
</BLOCKQUOTE>
<BLOCKQUOTE><BLOCKQUOTE><CODE>
setterm -reset &gt; <TT>/dev/tty1</TT>
</CODE></BLOCKQUOTE></BLOCKQUOTE>
<BLOCKQUOTE>
(note: the redirection operator on my stty
command is NOT backwards. stty performs<TT> ioctl()</TT>
calls on it's input device while setterm
words on it's output file descriptor. It looks
weird but stty was written a long time ago and
it actually made sense back then).
</BLOCKQUOTE>
<BLOCKQUOTE>
I've had cases where I could revive a console (from a
crashed X session or a wacked out SVGAlib program failure)
by running startx (from a remote session, even from a serial
login. That works sometimes (since the X server has to
reset quite a bit of the video and keyboard state as it
starts).
</BLOCKQUOTE>
<BLOCKQUOTE>
These kinds of console oddities are pretty rare.
It's usually the result of some buggy program that's
running with root privileges or some buggy driver
(which naturally is running with system/kernel
level access to the hardware). It could be a bit
of flaky hardware, too. It would be good to
figure out what is doing this. However, if this
is set up as a server, it may be that you don't
need the console all that much. You can treat it
like a "headless" system if you need to.
</BLOCKQUOTE>
<BLOCKQUOTE>
If you do decide to switch out hardware, try a
cheap replacement video card. Under Linux, in
server applications there is no point to using a
high end video card. Meanwhile the high end video
cards are most likely to have the cutting edge
technology and the highest chance of conflict with
other system components. Also make sure that any
"Plug and Pray" (PNP) settings are disabled in your
ISA peripherals and BIOS/CMOS.
</BLOCKQUOTE>
<BLOCKQUOTE>
If you think it's software then try attaching
strace to various processes that are bound to
your console. See if there's some oddity to
the system calls they're making before the lockup.
</BLOCKQUOTE>
<BLOCKQUOTE>
(Read the strace man page to understand a bit more
about this. Don't even bother if you don't know
the difference between a system call and a library
function. There's a pile of learning curve in
that direction).
</BLOCKQUOTE>
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<H5 align="center"><a href="http://www.linuxgazette.com/copying.html"
>Copyright &copy;</a> 2000, James T. Dennis
<BR>Published in <I>The Linux Gazette</I> Issue 51 March 2000</H5>
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