[PlanetCCRMA] About upgrades, distros and the rt-kernel

Fernando Lopez-Lezcano nando at ccrma.Stanford.EDU
Wed Jun 17 17:26:55 PDT 2009

On Thu, 2009-06-18 at 01:44 +0200, ailo wrote:
> I've installed fc10 on three machines, all of them old.
> Just migrated from Ubuntu, so I am not used to Yum.
> I followed the instructions at:
> http://ccrma.stanford.edu/planetccrma/software/installplanetnine.html
> I updated the system. Then Installed some apps + planetccrma-core, with
> the rt-kernel. Boot went fine, however logging in caused Xorg to crash.

It would help to know what is logged in /var/log/Xorg.0.log when Xorg
crashes. What type of video card are you using? What drivers?

> Then, after doing some research, I decided to reinstall, and NOT to
> upgrade my system before installing the planetccrma-apps and -core.
> This worked a lot better, however I still had to keep the fedora-updates
> checked in 'Software Sources' in order to be able to install the
> planetccrma packages. This must have meant that I still needed to
> upgrade a few packages from Fedoras repo in order to be able to install
> some of the planetccrma packages.

That would be correct.

> I know this is not a Planetccrma issue, however, I feel a bit lost in
> this update-jungle.
> Keep in mind, that the 'normal' kernel worked just fine at all times, so
> this must be a problem connected to the rt-kernel.
> I read somewhere that the rt-kernel is always behind the 'normal' one. 
> Is there a way to synchronize yum with the kernel-version you want to
> use? Would it help stability?

This is a complicated issue... sorry...

It could be that the rt kernel is too old for the newest X in Fedora 10,
in combination with the hardware you have. 

You could try installing a much newer rt kernel that is part of the
planetcore-testing repository. For that you need to activate that
repository by doing (as root):

  yum install planetccrma-repo-testing

and then:

  yum install kernel-rt

That should give you a much newer (2.6.29+) kernel and it might work. 

But that might still not be enough. Why? Because the rt kernel does not
include _all_ the patches that the Fedora kernel includes, especifically
the video card patches and new drivers that Fedora includes with their
kernels. Why? Those patches don't patch cleanly on top of the rt patches
and I don't have time to try to "fix" them... :-(

If all fails you can keep using the stock Fedora kernels, they are not
that bad in terms of latency (because the plain vanilla kernel has
gotten better over time in that respect). 

-- Fernando

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