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RT Kernel for RoseGarden

RT (Real Time) Kernel for RoseGarden

rosegarden_fail

Warning – RT Installation described below does not work on Maverick Meerkat Ubuntu Ver 10.10

If you have ever installed RoseGarden and especially a beginner attaining a sound or noise from this application can be a troublesome affair. This article aims to address this issue by explaining the process from a technical perspective to get RoseGarden and Jack Server to work and work together. I would explain from the outset I am not a musician I rather wish I was as understanding many of the concepts would have been a lot easier. This is rather a clinical approach and may not be the correct way but least, it does work as my images in this article will show.

Installing a different kernel for use with RoseGarden

In the image above RoseGarden appears to show that it requires a module to run I am not sure that this is the case or not, at least in Ubuntu or Mint initialising this command would return “module not found” and end in failure. A Real Time kernel is an optimised kernel especially for audio. Now it is possible to run Jack without a RT kernel however RoseGarden seems less forgiving (perhaps I am wrong, I don’t know).

Running Jack on it’s own without RoseGarden and a Real Time kernel can also fail to initialise properly especially when the “realtime” option is ticked (see second image).

jack_fail jackset

It is sometimes possible to allow Jack to run just by unticking the realtime option in the setup panel, RoseGarden once initialise still throws up the error but it may still work, but it will not work unless you have installed some Midi synths and audio plugins.

no_rt jackwk rosegdn1 roswgdn2

Howto Install a RealTime Kernel

For many of us myself included I have or at least thought I had little use for a Kernel other than that which was supplied by the likes of Ubuntu, Mint and so on. If I needed to change the kernel for some reason or some aspect of it, and the menu.lst file did not update after a new kernel was installed, well you could as a matter of last resort edit the file yourself. Well, that is an option not any longer editing of the “grub/menu.lst” used to be so easy and now, guess what they changed it in Grub version 2 time will tell if it is actually better.

Actually your kernel is updated more times than you are probably aware of, especially if you update your Desktop or Server system on a regular basis. There are a number of ways you can update your system from the padlock icon located somewhere on your screen Desktop or via the command line with “apt-get update” and “apt-get upgrade” but I should quickly point out that many files are updated when the command is invoked the kernel is only one of them and is updated not nearly so often. A system restart will follow a kernel update in almost all cases.

The focus of this article will be the installation of a “realtime” kernel, it is a howto to select and install access and confirm your chosen kernel is installed and is being used. The first thing we need do is determine the current kernel being used with your system this can be observed in any one of a number of ways the most common being at the boot menu. Now I am using LinuxMint “Helena Edition” and have found the menu does not appear when you press the escape button during bootup as before now you need to press the shift key and hold during bootup until the menu appears. There is however another more accurate way to determine your kernel which you can do from the command line.

#> uname -a

This will tell you exactly the kernel in use.

Now we know what you are using the chances are it is not an “RT” kernel if it is then you are using a system possibly modified and optimised to work with the Operating Systems you have chosen such as “64studio”, Ubuntu-Studio or perhaps Puredyne plus others” all of these variants of the Linux operating system feature low latency with regard to audio and video processing of applications which are highly favored in audio and video processing.

We will assume for the purpose of this article you like me are using a standard kernel and for some reason best known to yourselves want to install and use an “RT” (Real Time) kernel. First you will need to locate the “linux rt” kernel, select and install it. I have found searching for what I want from the command line most unhelpful so would suggest the synaptic package manager instead from your “system / administration” section which should come up with result like these.

linux-rt
linux-image-rt
linux-headers-rt

To install you need to obtain from your Synaptic Package Manager the three above packages after which you will need to complete the installation by following the remaining steps below.

These should be the only packages you need to select, any dependencies will be associated automatically all you need do is confirm installation. Now usually this kernel would be updated in the grub configuration so that when the menu is accessed the new kernel will appear in the list. Well the configuration does not get updated this is because grub2 is only sort of installed you can use “update-grub” as recommended but it does not work, (well, yes actually it does work) the difference is that it updates the version 1 grub configuration which is not accessed by version 2 of grub. So to get around this problem we use the command line to install “grub2”

#> sudo apt-get update && sudo apt-get upgrade && sudo apt-get install grub2

To simplify matters I have daisy chained the three separate commands into one.

This again will update the grub configuration only this time when you boot into your system holding down the shift key as you do so and the boot menu appears you will now see and be able to select the real time kernel as desired.

How do you know you are running a RealTime Kernel

Just like before after selecting the RT kernel from the boot menu all you need do is activate a terminal console screen and type in the following:-

#> uname -a

This will tell you if you are running the correct kernel, if you have confirmed you are running the correct kernel you will need to modify your Jack setup options this time to include “realtime” just tick the option.

jackset

Author: Derek Shaw - Page reference: 2080
Last modified: Derek Shaw - 2015-01-20

Categories: Uncategorised

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