Kernelmessage to usbstick?

Kernelmessage to usbstick?

[Hans de Bruin]

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.

-- 
Hans

Re: Kernelmessage to usbstick?

[Andi Kleen]

Hans de Bruin <bruinjm@xs4all.nl> 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.

-Andi

-- 
ak@linux.intel.com

Re: Kernelmessage to usbstick?

[Oliver Neukum]

Am Saturday 10 January 2009 23:53:15 schrieb Andi Kleen:
> Hans de Bruin <bruinjm@xs4all.nl> 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.

	Regards
		Oliver

Re: Kernelmessage to usbstick?

[Hans de Bruin]

Oliver Neukum wrote:
> Am Saturday 10 January 2009 23:53:15 schrieb Andi Kleen:
>> Hans de Bruin <bruinjm@xs4all.nl> 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.
> 

I just found out even a serial cable would not help, since the only comm 
device in my laptop ends in a build in modem. Since there is no parallel 
printer port either I will have to use pen and paper. In the mean time, 
rc1 broke my keyboard.

-- 
Hans

Re: Kernelmessage to usbstick?

[Mark Lord]

Oliver Neukum wrote:
> Am Saturday 10 January 2009 23:53:15 schrieb Andi Kleen:
>> Hans de Bruin <bruinjm@xs4all.nl> 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.

Re: Kernelmessage to usbstick?

[Hans de Bruin]

Hans de Bruin wrote:
> 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.
> 

The shutdown problem just disappeared.

-- 
Hans

Re: Kernelmessage to usbstick?

[Pavel Machek]

On Sat 2009-01-10 20:13:10, Hans de Bruin wrote:
> 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.

digital camera :-).

...or green display with *long* phosphor burn time.
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html