2007-08-27 11:21:40

by Esteban Fernandez

[permalink] [raw]
Subject: Pausing kernel boot messages

How do you pause the kernel boot messages ?

^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
kernel panic.

Thanks.


2007-08-27 11:53:33

by Hans J. Koch

[permalink] [raw]
Subject: Re: Pausing kernel boot messages

Am Montag 27 August 2007 13:21 schrieb Esteban Fernandez:
> How do you pause the kernel boot messages ?
>
> ^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
> kernel panic.

These are functions of a shell (like bash), which you haven't got yet during
kernel boot. You can read the kernel boot messages _after_ your system's up
using dmesg etc.
If you can't do that, e.g. because your kernel always hangs during boot, you
could enable a serial console in your kernel and watch/log your kernel
messages with a terminal program running on a different computer.

Hans

2007-08-27 11:58:53

by Andreas Schwab

[permalink] [raw]
Subject: Re: Pausing kernel boot messages

Hans-J?rgen Koch <[email protected]> writes:

> Am Montag 27 August 2007 13:21 schrieb Esteban Fernandez:
>> How do you pause the kernel boot messages ?
>>
>> ^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
>> kernel panic.
>
> These are functions of a shell (like bash),

Definitely not. The shell is not a console driver, it only uses it.

Andreas.

--
Andreas Schwab, SuSE Labs, [email protected]
SuSE Linux Products GmbH, Maxfeldstra?e 5, 90409 N?rnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."

2007-08-27 12:10:37

by Zilvinas Valinskas

[permalink] [raw]
Subject: Re: Pausing kernel boot messages

Esteban,

Alternatively, read Documentation/networking/netconsole.txt. Might help
or might not. It depends when system is crashing.

On Mon, 2007-08-27 at 13:53 +0200, Hans-Jürgen Koch wrote:
> Am Montag 27 August 2007 13:21 schrieb Esteban Fernandez:
> > How do you pause the kernel boot messages ?
> >
> > ^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
> > kernel panic.
>
> These are functions of a shell (like bash), which you haven't got yet during
> kernel boot. You can read the kernel boot messages _after_ your system's up
> using dmesg etc.
> If you can't do that, e.g. because your kernel always hangs during boot, you
> could enable a serial console in your kernel and watch/log your kernel
> messages with a terminal program running on a different computer.
>
> Hans
>
> -
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2007-08-27 12:14:07

by Hans J. Koch

[permalink] [raw]
Subject: Re: Pausing kernel boot messages

Am Montag 27 August 2007 13:58 schrieb Andreas Schwab:
> Hans-J?rgen Koch <[email protected]> writes:
>
> > Am Montag 27 August 2007 13:21 schrieb Esteban Fernandez:
> >> How do you pause the kernel boot messages ?
> >>
> >> ^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
> >> kernel panic.
> >
> > These are functions of a shell (like bash),
>
> Definitely not. The shell is not a console driver, it only uses it.

Right, I wasn't precise. But it's still possible that you don't have your
keyboard available during early parts of the boot process.

Hans

2007-08-30 19:16:05

by Jan Engelhardt

[permalink] [raw]
Subject: Re: Pausing kernel boot messages


On Aug 27 2007 14:13, Hans-Jürgen Koch wrote:
>> >> How do you pause the kernel boot messages ?
>> >>
>> >> ^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
>> >> kernel panic.
>> >
>> > These are functions of a shell (like bash),
>>
>> Definitely not. The shell is not a console driver, it only uses it.
>
>Right, I wasn't precise. But it's still possible that you don't have your
>keyboard available during early parts of the boot process.

Yes, but a common error is "could not mount root", which is way after the
keyboard has been initialized. *In fact*, you can start initramfs, have your
PgUp/PgDown keys available, and when you exit out of initramfs without a valid
root filesystem, you lose the keys again.


Jan
--

2007-08-31 16:58:34

by Chuck Ebbert

[permalink] [raw]
Subject: Re: Pausing kernel boot messages

On 08/27/2007 07:21 AM, Esteban Fernandez wrote:
> How do you pause the kernel boot messages ?
>
> ^S, Pause and Scroll lock do nothing and you can't Shift-Page-Up after a
> kernel panic.
>

You could try linux-2.6-debug-boot-delay.patch from Randy Dunlap,
included in the Fedora 7 kernel.