[LAU] Linux 3.2.0-rt Kernels on Debian Repos!

[Ralf Mardorf]

On Thu, 2012-02-23 at 12:00 +0000,
linux-audio-user-request at lists.linuxaudio.org wrote:
> Message: 4
> Date: Wed, 22 Feb 2012 19:24:47 +0200
> From: David Baron <d_baron at 012.net.il>
> Subject: [LAU] Linux 3.2.0-rt Kernels on Debian Repos!
> To: linux-audio-user at lists.linuxaudio.org
> Message-ID: <201202221924.48273.d_baron at 012.net.il>
> Content-Type: Text/Plain; charset=us-ascii

> FATAL: modpost: GPL-incompatible module nvidia.ko uses GPL-only symbol
> 'migrate_enable'

Don't use a borked distro! If your distro don't provide the nv driver,
but replace it with an experimental driver, that knowingly isn't working
for half of the NVIDIA graphics on the market, such as the nouveau
driver, than your distro is borked!

OTOH, for Debian it's easy to build kernel packages yourself.

Doing that, offend the license:

  sed -i \

's/EXPORT_SYMBOL_GPL(migrate_enable);/EXPORT_SYMBOL(migrate_enable);/' \
  	  kernel/sched.c
  
  sed -i \

's/EXPORT_SYMBOL_GPL(migrate_disable);/EXPORT_SYMBOL(migrate_disable);/'
\
  	  kernel/sched.c
  
  sed -i \

's/EXPORT_SYMBOL_GPL(__rt_mutex_init);/EXPORT_SYMBOL(__rt_mutex_init);/'
\
  	  kernel/rtmutex.c

> ------------------------------
> 
> Message: 5
> Date: Wed, 22 Feb 2012 19:04:48 +0100
> From: "rosea.grammostola" <rosea.grammostola at gmail.com>
> Subject: Re: [LAU] Linux 3.2.0-rt Kernels on Debian Repos!
> To: linux-audio-user at lists.linuxaudio.org
> Cc: Debian Multimedia Maintainers
>         <pkg-multimedia-maintainers at lists.alioth.debian.org>
> Message-ID: <4F452E40.6090004 at gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed

> 
> Cool! All though we don't really need -rt anymore afaik. Lowlatency 
> would be good enough.

I build, but never tested a full preempt kernel with threadirqs set.
Anyway, this already was claimed for preempt enabled kernels before
2.6.29 and at least at this time it wasn't true. Depending to your
workflow and your cognitive ability, you might wish to get less audio
latency with hard real-time MIDI jitter.

People often blame MIDI of not being capable to do some things. I
recommend to get rid of ms of jitter and to use several PCI MIDI
interfaces, before claiming that MIDI shouldn't be able to do something.
IMO a rt patched kernel is a step into the right direction to get hard
real-time.

2 Cents,
Ralf