NOTE
With the newest kernels, it's enough to add
these lines to /etc/security/limits.conf :
@audio - rtprio 99
@audio - memlock 512000
@audio - nice -19
and this line to /etc/pam.d/su :
session required pam_limits.so
Then you don't need an -rt patched kernel like explained in this HowTo.
This how-to is part of the AVLinux install but I like it, so I'll put it online here.
(There's also this howto by Ralf Maldorf)
HOWTO BUILD A CUSTOM -RT KERNEL FOR DEBIAN (in 13 steps)
#1: USING Kernel 2.6.29.6 AS AN EXAMPLE
*Check for latest stable Kernel at www.kernel.org (+ matching -rt patch) and update text as necessary*
To be more clear about matching -rt patch: in this example the number 2.6.29.6 must be both in the kernel and -rt patch names.
#2: INSTALL DEPENDENCIES (AS ROOT)
apt-get install build-essential bin86 kernel-package libqt3-headers libqt3-mt-dev wget libncurses5 libncurses5-dev
#3: MOVE TO /usr/src *Where Kernel is to be built
cd /usr/src
#4: MAKE YOURSELF ROOT
su
Password:
#5: DOWNLOAD AND UNPACK THE KERNEL SOURCE PACKAGE
wget -c http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.29.6.tar.bz2 && tar -xvjf linux-2.6.29.6.tar.bz2
#6: REMOVE LINK TO LINUX DIR, MAKE NEW LINK TO NEW KERNEL, MOVE TO LINUX DIR
rm -rf linux && ln -s /usr/src/linux-2.6.29.6 linux && cd /usr/src/linux
#7: DOWNLOAD THE REALTIME (-rt) KERNEL PATCH *MUST MATCH WITH KERNEL VERSION*
wget -c http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.29.6-rt23.bz2
#8: APPLY THE -RT PATCH TO KERNEL
bzcat patch-2.6.29.6-rt23.bz2| patch -p1
#9: IMPORT YOUR CURRENT KERNEL CONFIGURATION AND OPTIONS
cp /boot/config-$(uname -r) .config && yes "" | make oldconfig
#10: CREATE YOUR NEW KERNEL CONFIGURATION (WITH GUI) OR USE CLI OPTION BELOW. #YOU WILL WANT TO CONFIGURE WITH "Preemptible Kernel" AND "1000hz" TIMING #AT THE VERY LEAST
make xconfig
#10: CREATE YOUR NEW KERNEL CONFIGURATION (WITH CLI)
make menuconfig
#11: BUILD A KERNEL PACKAGE TO INSTALL & SHARE
make-kpkg clean
#12: THEN THIS
fakeroot make-kpkg --initrd --append-to-version=-rt kernel_image kernel_headers
#13: IF ALL GOES WELL YOU WILL FIND 2 DEB PACKAGES IN /usr/src/ WITH A KERNEL IMAGE AND KERNEL HEADERS THAT CAN BE INSTALLED WITH SYNAPTIC
More tutorials: