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Links Operating Systems BSD

FreeBSD For The Linux Administrator 17

Posted by Nik from the NP:-Now-and-Then dept.
LinuxWorld carries an article by Michael Lucas, Customizing The FreeBSD Kernel. The twist is that it's written partly from the perspective of a Linux user, highlighting the similarities and differences between the two systems.
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FreeBSD For The Linux Administrator More

FreeBSD For The Linux Administrator

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  • Oh, and people, never do "make depend all install" like the article suggests. Make doesn't rescan the dependency file after the "depend" step, so the kernel is built with possibly incorrect dependency information.

    I see .. one would need to force make into rescanning the dependencies after it processed a 'depend' target.

    Not sure if this can be done without modifying make. In either case it would be very nice to have some warning about this case somewhere.

  • it's called "kernel" not "kernal" ....
  • Fun thing is on FreeBSD you could have those same 19 kernels sitting in your system ... being able to boot all 19 of them ... and STILL not needing to fiddle with any config-file/binary tool to allow you to boot them like LILO

  • Darn. (Score:1)

    by DES ( 13846 )
    I typed the wrong URL for the handbook section on kernel configuration [freebsd.org].

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  • Agreed. It's been discussed before. I think it would greatly help matters along if you just took the latest LINT, reformatted it as you see fit, and submitted the patches. I think Java would be a good choice of language - imagine the configuration editor running as an applet somewhere on the FreeBSD web site...

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  • Personally I just add a few lines to the lilo.conf file and there we are... we have choice... new old, very old... older... 2.0 whatever you like (I do a lot of testing of the ac-patches (Alan Cox for you BSD folks who don't know Linux hackers by abrev.). And I got about 19 kernels in my LiLo right now.

  • Nice (Score:1)

    by hattig ( 47930 )
    Useful for your average Linux admin, but it doesn't go into a lot of depth. FreeBSD hasn't got the best kernal docs and system, and LINT isn't the most descriptive and helpfil file ever.

    Still, the default kernal is good enough for most people!

  • Thuspd! Wipple Wipple.

    (sound of me sticking my tongue out and blowing a raspberry, then wiping the monitor with a tissue)

    Okay, Kernel.

    Linux Kernel in a Nutshell - O'Reilly.

  • Why should I have to ?

    If the tool is sufficiently advanced it should do that for me fairly transparently. While FreeBSD doesn't automatically save more than 1 version of the kernel, not updating and re-running something (ie. lilo) won't shut my system down until I can get a recovery diskette and get into the system, find out what I messed up, re-run lilo and try again..

    With FreeBSD, I just load the last good kernel, boot with it and I am running again.. No recover diskette needed..

  • No one does it ?

    Sorry.. I always do it... Its a habit when I tweak the kernel config file.. make depend, make all, make install...

    I bet a large majority of people building kernels do the depend step.

  • What I really love about the FreeBSD kernel compilation is that all generated source files, header files, and object files are kept in separate compile directories (one for each kernel configuration). This way you can compile multiple kernels simultaneously without having the different kernel compilations interfere with each other. I haven't compiled a Linux kernel in ages though, so it might be that this is supported nowdays.
  • I much prefer FreeBSDs text file configuration to that on linux, but it would be nice to have a generator program, which would go through *all* the possible choices, and create an initial KERNEL file for you to edit.
  • I have thought long and hard about such a tool (like a Tcl/Tk or Java program) that let you do a kernel build from config to installation but I am not quite certain that the *current* format of LINT would lend itself to that. Maybe if someone went through LINT and created a standard and unified format for the nots and documentation, it would work, but not until then.
  • Agreed - I have done both Linux and FreeBSD kernal compiles with success - although I cheat and write the Linux compiles to a boot disk so I can test them before committing my changes.

    I like the fact the FreeBSD will keep a rescue kernal which is easy to boot if all goes wrong, but LINT is not the best type of documentation in the world. OTOH it is pretty easy to compile out all the crud like redundant ethernet and scsi and whatever that is installed by default, and you can be guaranteed to edit the kernal config file remotely via a text terminal without the useless interrogation of the Linux system.

    MenuConfig on Linux is okay, fine for brutalising a kernal first time around before fine-tuning it. FreeBSD would benefit from a tool like this, but done better.

  • I have been using Linux for about 2 years and FreeBSD for about 3 years.. I still find that the FreeBSD kernel rebuild is lots easier.

    Also, the fact that its more difficult to make your system unbootable with FreeBSD (since by default when you install a new kernel it saves your old one) and if your new kernel doesn't work, you can get back to the old one more easily [ no worries about munging up the system so bad you need a recovery disk to re-do LILO ].

    I was able to get a working kernel from FreeBSD the 1st try (because of the Online Handbook [freebsd.org] being decent...)

    I have only rebuilt a linux kernel once (when I needed more than the default 4 software raid drives in RH 5.2).

    I also think editing 1 file verses the 5 miles of check boxes for a Linux kernel is easier. You can also more easily change 1 thing then rebuild your kernel and keep going..

  • Re:A nice addition (Score:3)

    by howardjp ( 5458 ) on Sunday March 26, 2000 @08:06PM (#1177506) Homepage
    That would be cool if it could generate pre-built kernels or custom installation floppies that way via the web :)

  • Unfortunately... (Score:3)

    by DES ( 13846 ) <des@des.no> on Sunday March 26, 2000 @05:59AM (#1177507) Homepage
    ...the article in question contains multiple factual errors. The general feeling I get from reading it is that it obscures rather than clarifies the issue. FreeBSD does have a handbook [freebsd.org] which goes to some lengths to explain these things [freebsd.org]. Oh, and people, never do "make depend all install" like the article suggests. Make doesn't rescan the dependency file after the "depend" step, so the kernel is built with possibly incorrect dependency information.

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