Alternatives to serial console for oops.

Alternatives to serial console for oops.

[James Courtier-Dutton]

Hi,

I wish to view the oops that are normally output on the serial port of 
the PC. The problem I have, is that my PC does not have a serial port.
Are there any alternatives for getting that vital oops from the kernel 
just as it crashes apart from the serial console.
Could I get it to use some other interface? e.g. Network interface.
Parallel port is also not an option.

James

Re: Alternatives to serial console for oops.

[Willy Tarreau]

Hi,

On Sun, Nov 27, 2005 at 03:52:27PM +0000, James Courtier-Dutton wrote:
> Hi,
> 
> I wish to view the oops that are normally output on the serial port of 
> the PC. The problem I have, is that my PC does not have a serial port.
> Are there any alternatives for getting that vital oops from the kernel 
> just as it crashes apart from the serial console.
> Could I get it to use some other interface? e.g. Network interface.
> Parallel port is also not an option.

The netconsole patch should let you send it over a network interface,
but I've not used it much so I won't be able to help. kmsgdump will
let you write it on a floppy disk, but I bet that you don't have any
if you don't have any serial nor parallel ports.

VMWare may help if you are mainly trying to debug a kernel and not
using it for production.

Regards,
Willy

Re: Alternatives to serial console for oops.

[Jesper Juhl]

On 11/27/05, James Courtier-Dutton <James@superbug.demon.co.uk> wrote:
> Hi,
>
> I wish to view the oops that are normally output on the serial port of
> the PC. The problem I have, is that my PC does not have a serial port.
> Are there any alternatives for getting that vital oops from the kernel
> just as it crashes apart from the serial console.
> Could I get it to use some other interface? e.g. Network interface.
> Parallel port is also not an option.
>
Netconsole (Documentation/networking/netconsole.txt)
Digital camera to take a photo of the screen.
Pen & paper to manually write down the Oops.

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post  http://www.catb.org/~esr/jargon/html/T/top-post.html
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Re: Alternatives to serial console for oops.

[Mateusz Berezecki]

On 11/27/05, Jesper Juhl <jesper.juhl@gmail.com> wrote:

> Pen & paper to manually write down the Oops.

you really need to be _desperate_  :-) I tried this literally _once_ .

Re: Alternatives to serial console for oops.

[Michael Tokarev]

Jesper Juhl wrote:
> On 11/27/05, James Courtier-Dutton <James@superbug.demon.co.uk> wrote:
> 
>>Hi,
>>
>>I wish to view the oops that are normally output on the serial port of
>>the PC. The problem I have, is that my PC does not have a serial port.
>>Are there any alternatives for getting that vital oops from the kernel
>>just as it crashes apart from the serial console.
>>Could I get it to use some other interface? e.g. Network interface.
>>Parallel port is also not an option.
> 
> Netconsole (Documentation/networking/netconsole.txt)

I wasn't able to capture an OOPS using netconsole from my
arm-based firewall box -- the output comes too fast and receiving
end only captures some random parts of the OOPS.  I doubt the
receiving box is too slow (2.4GHz Pentium-IV, Intel GigE ethernet),
so it must be the sending end which is trying to generate packets
faster than it's own NIC can transmit them... or something else.

Even "normal" serial console does not work here for this device:
serial port on the box has no flow control, and at 9600 it still
loses some parts of the OOPS, or especially a sysrq-t output
(which is much larger than a typical OOPS).

> Digital camera to take a photo of the screen.

Not all systems has a screen (my router certainly does not).
Also, even for "usual" PC, amount of information in an OOPS
is larger than a screen, so most important part of the OOPS
(several lines on the top) is lost.

> Pen & paper to manually write down the Oops.

The same problem as above with a camera.

This stuff worked perfectly in 2.4 kernel, where it was possible
to use keyboard to scroll to the beginning of an OOPS - only
half a screen and we're here (well, sometimes it is larger,
but Shift-PgUp still worked).  Now, when keyboard does not work
anymore, it's not possible.  As is not possible to reboot the
system using "Three Finger Solution" (Ctrl-Alt-Del) -- some modern
systems does not have "Reset" button, so in order to reboot after
an OOPS, one have to power-cycle the box...

It'd be really nice to have keyboard back in "OOPS mode", as 2.4
had...

Oh well.

/mjt

Re: Alternatives to serial console for oops.

[Michael Frank]

On Sunday 27 November 2005 16:52, James Courtier-Dutton 
wrote:
> Hi,
>
> I wish to view the oops that are normally output on the
> serial port of the PC. The problem I have, is that my PC
> does not have a serial port. Are there any alternatives
> for getting that vital oops from the kernel just as it
> crashes apart from the serial console. Could I get it to
> use some other interface? e.g. Network interface.
> Parallel port is also not an option.
>
> James

I use Netconsole for routine monitoring.

See Documentation/networking/netconsole.txt

Example for kernel command line
netconsole=1024@192.168.2.131/eth0,4450@192.168.2.1/00:00:0E:5F:15:64

You don't want to hassle with netcat.

Many sysloggers can log udp

I use syslog-ng. Excerpts from configuration:

source netlog { 
	udp(ip(0.0.0.0) port(4450)); 
};

destination netlog
{ 
	file("/var/log/netlog"); 
};

log 
{ 
	source(netlog); 
	destination("netlog"); 
	flags(final); 
};

Re: Alternatives to serial console for oops.

[Randy.Dunlap]

On Sun, 27 Nov 2005 15:52:27 +0000 James Courtier-Dutton wrote:

> Hi,
> 
> I wish to view the oops that are normally output on the serial port of 
> the PC. The problem I have, is that my PC does not have a serial port.
> Are there any alternatives for getting that vital oops from the kernel 
> just as it crashes apart from the serial console.
> Could I get it to use some other interface? e.g. Network interface.
> Parallel port is also not an option.

If the oops occurs after booting (e.g., it's in a module that you
can load after boot to cause the oops) and if you have USB ports
and a usb-serial converter device, you should be able to use
usb-console output to capture the oops.

---
~Randy

Re: Alternatives to serial console for oops.

[Geert Uytterhoeven]

On Sun, 27 Nov 2005, Mateusz Berezecki wrote:
> On 11/27/05, Jesper Juhl <jesper.juhl@gmail.com> wrote:
> 
> > Pen & paper to manually write down the Oops.
> 
> you really need to be _desperate_  :-) I tried this literally _once_ .

Obviously you never flashed the screen using 8 colors (3 bits of information),
to transfer a crash dump message...

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

Re: Alternatives to serial console for oops.

[Jan-Benedict Glaw]

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On Mon, 2005-11-28 11:02:03 +0100, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Sun, 27 Nov 2005, Mateusz Berezecki wrote:
> > On 11/27/05, Jesper Juhl <jesper.juhl@gmail.com> wrote:
> > 
> > > Pen & paper to manually write down the Oops.
> > 
> > you really need to be _desperate_  :-) I tried this literally _once_ .
> 
> Obviously you never flashed the screen using 8 colors (3 bits of information),
> to transfer a crash dump message...

In 1998, we used a video camera to capture a long-scrolling Oops at
the CLOWN cluster project in the University of Paderborn, Germany...
So we could finally fix the problem and make this Cluster event a real
success 8^P

MfG, JBG

-- 
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