[PlanetCCRMA] Re: Reliability of the fc2 ccrma kernel?

Mark Knecht Mark Knecht <markknecht@gmail.com>
Thu Nov 18 13:18:01 2004

On Thu, 18 Nov 2004 19:15:56 +0800, Timo Sivula <timo.sivula@luukku.com> wrote:
> Mark,
> On Wed, 2004-11-17 at 23:42, Mark Knecht wrote:
> >  On this laptop most of my time is spent in Gentoo, not FC2, and
> > under Gentoo I can run Jack under low load at 2/16 with no xruns at
> > all. Yes, that's .7mS latency! Now, low load is not that interesting,
> > but it shows it can be done with the right hardware and kernel.
> This certainly sounds interesting. You wrote earlier that this was a
> heavily patched kernel. I would need a kernel with a stack size bigger
> than the 4 kb to make my ndiswrapper work, so I guess I have to patch my
> kernel anyhow.
> Would it be possible for you to put the sources and/or .config file for
> your kernel somewhere ont he net to try out on Fedora Core 2 here?
> br, Timo

   I'd be happy to send you the config file that I'm using on my
Gentoo laptop. I have more faith in this kernel than what I'm running
under FC2 right now. I'll forward that off list if it's OK.

   As for building it, when I was doing this (Oct. 1st) I got the
following instructions from Lee Revell

This is all you really need to know about patching.  You need to start
with 2.6.8 (not and apply patches in this order:


That's really all there is to it.  The easiest way to configure the
kernel is to cd to the kernel source directory, then do:

zcat /proc/config.gz > .config
make oldconfig

and accept the defaults for every config option.  This will give you the
closest possible config to the kernel you are already running.

At this point I had a good kernel but all the interrupts were threaded
by default. If I wiggled my USB mouse I caused xruns, so I had to
adjsut my sound card's interrupt. You will need to adjust this command
for your soundcard, but cat /proc/interrupts will tell you where it is
and then you'll be able to make the sound card non-threaded:

* Mark Knecht <markknecht@gmail.com> wrote:

>   5:      64019   IO-APIC-level  ATI IXP  0/64019

is this the soundcard IRQ? Just to make sure, have you done:

       echo 0 > /proc/irq/5/"ATI IXP"/threaded

to turn off irq threading for the sound IRQ? (i.e. to mark it highprio)


>From here I still had a few things to deal with.

a) UMP not SMP
b) Disabling ACPI in the kernel
c) Patching in the realtime-lsm stuff for 2.6.9 and then making a
realtime group to grant this capability to.

If all of this seems like something you want to try then I can
hopefully help you go through it. I found it pretty difficult, and
unfortunately I keep horrible notes. Basically I jsut have the email
threads that were passed around when I did it.

Currently I need to do this again myself for my HDSP 9652 machine, but
the whole day has been ruined by a miserable ndiswrapper experience
that completely hangs my sons machine when I do the modprobe step.
It's now 1:15 and I've not accomplished much of anything except
getting upset.

Let me know if you want this config file.