Ingo Molnar <mingo <at> elte.hu> writes:

i'm pleased to announce the v2.6.21.4-rt11 kernel, which can be 
downloaded from the usual place:

     http://people.redhat.com/mingo/realtime-preempt/

more info about the -rt patchset can be found in the RT wiki:

     http://rt.wiki.kernel.org

-rt11 is a bit more experimental than usual: it includes the CFS 
scheduler. Several people have suggested the inclusion of CFS into the 
-rt tree: the determinism of the CFS scheduler is a nice match to the 
determinism offered by PREEMPT_RT. The port of CFS to -rt was done by 
Dinakar Guniguntala. Tested on i686 and x86_64.

to build a 2.6.21.4-rt11 tree, the following patches should be applied:

    http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.21.4.tar.bz2
    http://people.redhat.com/mingo/realtime-preempt/patch-2.6.21.4-rt11

	Ingo

I've tried to compile it, but i've got the following:

  GEN     .version
  CHK     include/linux/compile.h
  UPD     include/linux/compile.h
  CC      init/version.o
  LD      init/built-in.o
  LD      .tmp_vmlinux1
kernel/built-in.o: In function `__schedule':
(.sched.text+0xe0): undefined reference to `pick_next_task'
make[1]: *** [.tmp_vmlinux1] Ошибка 1
make[1]: Leaving directory `/usr/src/linux-2.6.21.4-rt11-cfs17-arsenic'
make: *** [debian/stamp-build-kernel] Ошибка 2

It seems that patch is broken.