Re: Kernelmessage to usbstick?

[Mark Lord]

Oliver Neukum wrote:
> Am Saturday 10 January 2009 23:53:15 schrieb Andi Kleen:
> > Hans de Bruin <bruinjm@xxxxxxxxx> writes:
> >
> > > Would it be possible to send kernel messages to an usbstick? On
> > > poweroff my laptop displays a kernel trace and a final message:
> > > poweroff[3114] exited with preempt_count 2
> > > /etc/rc.d/rc.0: line 265: 3114 Segementation fault /sbin/poweroff.
> > > I don't have a serial cable within reach, but plenty of usbsticks.
> > There's a mtdoops.c indeed, but it currently only works on
> > MTD controlled flash devices, not usb sticks.
> >
> > However usb sticks would need the USB subsystem to be running and it's
> > unlikely that will be the case really late in poweroff.  So it might
> > not help.
>
> USB in turn needs PCI, interrupts and DMA.
..

Dunno about an oops, but I currently use a USB device to
display debug messages from the shutdown procedure,
all the way to kernel_halt().

So long as the Oops doesn't kill too much low level stuff,
it's probably feasible.  Except for the very slow write times
for many USB storage devices.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/