Supporting Multiple Kernel Versions
The kernels can be installed using the InstallKernel.pl script. InstallKernel.pl takes the full name of the kernel distribution file as input, with the “.tar.bz2” extensions. First, it checks that the distribution will not overwrite any existing file—if so, it aborts execution unless you specifically tell it to go ahead. It installs the kernel and its modules, and adds an entry to /etc/lilo.conf for this kernel. It is quite careful about how it does this. It creates a backup copy of /etc/lilo.conf, then scans it line by line until it finds a root= entry. It uses this to set the root for the new kernel. If it finds a later root= entry that specifies a different root partition, it will warn you, but will continue, using the first one it found. It will not add an entry if it finds an existing entry for this kernel image. The last thing it does is show you the differences between the saved lilo.conf and the one it has just created. InstallKernel.pl will not run LILO for you—you must do that yourself.
Another script, InstallHeaders.pl, will take care of installing the header files for you. The headers are installed as subdirectories of /usr/src/linux-headers. If you set the link /usr/src/linux to point to one of these installed sets of header files, you can compile your driver or program for a version of the kernel different from the one you are actually running. I make use of this to compile the ARLA AFS clone for all the kernels I support, without rebooting my machine.
Whichever distribution of Linux you are using, you will probably have to modify the way it decides which set of kernel modules to use. The details vary from distribution to distribution, so it is not possible to describe all the necessary changes here.
Since these kernels rely heavily on the use of modules, you may also need to create an initial RAM disk for your specific machine. This is certainly true if you have a SCSI-based system. See the man page for the mkinitrd command for details.
In order to clone the repository to build your own kernels, copy the contents of the /bin and /source directories, and modify them as you wish. KernelBuild.sh will need modifying in order to set the MY_* variables correctly. KernelConfig.exp may also need modifying to enable or disable any specific options—this may not be a trivial task. KernelBuild.cmds will need to be modified if you wish to actually change the way the kernels are built. The other scripts should never need to be altered.
At present, about 30 kernel source distributions are included in the repository, representing kernels from 2.0.34 to 2.0.36 and 2.2.0 to 2.2.7 with various patches. As the person who manages the machines running these different kernels, I find that this standardization has simplified my tasks considerably.
Tony Wildish received a Ph.D. in High Energy Particle Physics from Imperial College, London, in 1989. His career evolved from programming in Fortran to C and C++ while working at CERN. He became a systems administrator four years ago, and discovered Linux as a means of practicing his job while at home. Currently, he works at CERN for one of their experiments in preparation for the Large Hadron Collider, due to be commissioned in 2005. He enjoys Greek wine, Greek beaches and Greek food, as well as reading, and is especially fond of Terry Pratchets' Discworld series. His goal in life is to go on holiday and stay there. Tony can be reached via e-mail at email@example.com.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
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