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System stuff
The Linux Kernel
The kernel is the core of linux and provides all services that programs need to interface with the hardware. There are two kernels in the Planet CCRMA package collection. The RedHat or Fedora Core kernels are the latest versions of the stock RedHat or Fedora Core kernels with a couple of patches added so that it has capabilities enabled (and you can use Jack as a normal non-root user). The Planet CCRMA kernel has more low latency optimizations but may not work on all the hardware that the RedHat kernel supports (because the RedHat kernel has a lot of additional patches to fix bugs and add drivers).
Planet CCRMA kernel version 2.4.26-1.ll
The 2.4.26-1.ll kernel rpms contain:
- kernel 2.4.26: the original Linus kernel, includes ACPI
- preemptible kernel patch
- low latency patch
- drm low latency patch
- drm updates from redhat: up to date drm interface
- variable Hz: with Hz configured to 1000Hz
- alsa rtc patch
- capabilities patch: enable capabilities
- dma for audio cd extraction
- lm_sensors 2.8.2 kernel modules
- nfs patches
- usb fix for unicorn usb drivers
RedHat kernel version 2.4.20-31.1.caps
The 2.4.20-31.1.caps kernel rpms contain:
- All the original RedHat patches and configuration plus:
- drm low latency patch
- alsa rtc patch
- capabilities patch: enable capabilities
Fedora Core kernel version 2.4.22-1.2188.nptl.caps
The 2.4.22-1.2188.nptl.caps kernel rpms contain:
- All the original RedHat patches and configuration plus:
- drm low latency patch
- capabilities patch: enable capabilities
Most distributions come with heavily patched kernels and include functionality upgrades, fixes for well known bugs, upgrades, etc. The kernel I'm using is almost stock Linus (ie: does not have that many patches applied to it). Here is a description of some of the patches I have added and why:
- low latency patch:
this
patch tries to decrease the typical scheduling latency of the 2.4.x
kernels. This is necessary if you plan on using audio with very short
latencies and want dropout free performance (this is just one of the
many factors that affect audio performance under linux, see a later
section on tuning for other, sometimes more important tuneups).
- preemptible kernel patch:
makes the kernel
preemptible, this also increases responsiveness of the whole
system. There is a matching preemt lock break patch that I have not
applied. It does the same thing as Andrew's patch but it is less
complete and thus the resulting kernel has more high latency points
than one patched with Andrew's patch.
- capabilities patch:
activates capabilities in the kernel. This will
enable you to run audio applications with real-time priviledges
without having to run them as root or suid root. Jackstart (part of
the Jack Audio Connection Kit) or givertcap use capabilities for these
purposes.
Rpms:
ALSA sound drivers
The ALSA sound drivers are a set of kernel modules and libraries and utilities that provide a high quality sound device driver.
Planet CCRMA uses a recent (and hopefully stable) version extracted from ALSA cvs. The current version corresponds to CVS dated 20040417.103251.
The Planet CCRMA ALSA driver is automatically installed when installing the Planet Core components.
Rpms:
MidiShare
``MidiShare is a musical operating system for Macintosh (MacOS Classic and MacOSX), Windows 3.1, Windows 95/98, Windows NT/2000/XP, Atari and Linux. Result of many years of research and development undertaken by Computer Music Research Laboratory of Grame, MidiShare provides high level services to the field of computer music and MIDI applications.''
The Planet CCRMA MidiShare kernel drivers are automatically installed when installing the Planet Core components.
To install the MidiShare library type:
|
apt-get install midishare
|
To install the development files type:
|
apt-get install midishare-devel
|
The core of MidiShare is a kernel module, you probably want to activate the automatic load of the module at boot time:
|
/sbin/chkconfig --add MidiShare
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After activating the service you can reboot, or start it manually by typing:
|
/etc/rc.d/init.d/MidiShare start
|
Rpms:
MidiShare Player
``This library allows to develop multi-tracks synchronisable MidiShare sequencers.''
To install the MidiShare Player library type:
|
apt-get install midishare-player
|
To install the development files type:
|
apt-get install midishare-player-devel
|
Rpms:
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