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Dynamic /bin support on FreeBSD

Posted by michael on from the ymmv dept.

Dan writes "Gordon Tetlow has put together a patch to have /bin dynamically linked on FreeBSD. This is the first step on the way to having everything play nicely with ongoing work on getting NSS into the system. He cautions that the patch is preliminary and should probably be installed on a test machine."

4 of 54 comments (clear)

  1. Re:Why by Piquan · · Score: 3, Interesting

    That's good for who needs this. As for why, the NSS code works by dynamically loading the necessary backends. That's presumably why a dynamic /bin and /sbin are needed.

    So, my question is, why are /bin and /sbin traditionally static? Gordon's patch pretty much just sets them to dynamic linkage, and puts some libs and rtld in /lib. I'd think that if having /bin and /sbin dynamically linked was kosher, tho, that they would be. So I'm a little worried about this patch.

  2. Re:Why by aridhol · · Score: 3, Interesting
    /bin and /sbin need to be usable when only the root has been mounted. That means that they can't dynamically link to anything that's not in the root. That includes /usr/lib, which is where most dynamic linking takes place.

    I don't know why they needed to be completely static, as /lib still exists, so they should be linkable with libraries in there.

    It's probably just a safeguard against accidentally linking to a library in /usr/lib, just to have them fail when they're most needed.

    --
    I can't say that I don't give a fuck. I've just run out of fuck to give.
  3. Re:Why by renehollan · · Score: 4, Interesting
    Hopefully that one file would not be damaged in fs corruption.

    Holy light bulb, Batman! (well, JDizzy, any way, to give proper credit). You've just given me an idea!!

    Given that some executables are more important than others in reparing broken filesystems, this situation particularly exacerbated with crunched binaries, why not add error correcting codes to them, and use inteleaving techniques to mitigate single block errors? Yes, they would grow, but not likely to the limit of multiple complete copies.

    Also, for sensitive dynamically linked libraries, perhaps the directory structure could be modified to have a common LD_LIBRARY_PATH for some system directories. Heck, never mind a mod: just make the loader sensitive to .ldpath symlinks in the directory of the executible.

    --
    You could've hired me.
  4. Re:Why by JDizzy · · Score: 2, Interesting

    Right!

    I'm all for a really small /rescue partition with crunched init, fsck, mount, sh, and a few other essential tools to recover a broken system. The kernel could be altered in such a way that if it couldn't mount the root file system, it could mount the /rescue FS, and the fsck could happen. This would be a FreeBSD (shoot me) "safe mode" of sorts.

    If things were so broken that you couldn't fix them with the various built-in ways, a "rescue disk" (aka bootable cdrom, floppy) would have to be used to mount a pseudo root to in turn fsck the real root FS.

    --
    It isn't a lie if you belive it.