Re: Serial Console Support in Kernel
On Thu, Jun 12, 2008 at 10:42:49AM +0200, Ingo Juergensmann wrote:
> On Thu, Jun 12, 2008 at 09:28:40AM +0200, Geert Uytterhoeven wrote:
>
> > On Thu, 12 Jun 2008, Ingo Juergensmann wrote:
> > > Would be nice to have, yes, but it's difficult to use when there's a
> > > non-booting kernel and you can't change the commandline remotely to boot
> > > another kernel. ;)
> > One of my wild plans is to get kexec working. Then you can boot your test
> > kernel using kexec. If it crashes, just reboot, and the normal bootloader
> > boots the known-good kernel.
>
> Yes, that would be great, especially when the IP power switches are
> installed at the data center. ;)
>
> IIRC, Smurf did some Amiga Shell scripting to emulate a similar behavior:
> if a certain file exists, rename it and boot that file/kernel. On the next
> boot the old kernel is loaded. That way a new kernel could be tested and if
> it's working properly it can be installed the proper way as the default
> kernel.
>
> Hmmm, maybe I (or someone else) can write such a script...
I wrote a couple of scripts which are now used on crest and kullervo to
switch betwen different kernels, taking into account if the last kernel booted
successfully or not. There are not very pretty, but they seem to do the job.
You should be able to see them on crest/kullervo.
> > > A real Amiga bootloader with serial console would be really great for this!
> > > ;)
> > Hey, amiga-lilo does have serial support!
>
> Oh, amiga-lilo is actually working? Last I heard was that it had some issues
> and development was stuck.
My last try with Amiga-lilo created a crashing bootblock, there were
problems on 060s...
> > > > debug=ser is active once consoles have been set up (and it looks like you
> > > > should be able to use it as command console as well).
> > > Well, when the consoles are up you can use the normal serial console as
> > > well. I don't know what's the difference when you set debug=ser without
> > > looking it up...
> > debug=ser also gives you kernel messages, inclusing early debug
> > console=ttyS0 gives you `late' kernel messages, plus user space console
>
> Ah, ok, I'll add debug=ser on Elgar then...
>
> > > Anyway, it would be nice to have a serial console (system messages during
> > > boot) as soon as possible and we should setup at least Crest as well for
> > > using such a serial console. Due to it's VGA output and the FlickerFixer,
> > > Kullervo don't need this as urgent as Crest and Elgar, IMHO...
> > Then you should probably use `debug=ser console=ttyS0', and set up
> > amiga-lilo to use the serial console.
>
> Well, I would prefer to test amiga-lilo locally before setting it up on
> remote hosts. ;)
> But adding the kernel params is a quick fix... ;)
>
> Erm, where can I get amiga-lilo? Aminet?
I think there was a CVS on kullervo with the latest(?) source. I did build a
package of it a little while ago...
http://people.debian.org/~cts/debian-m68k/amiga-lilo/
I hope that is not the current source.
Christian
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