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I upgraded from 9.04 to 10.10 a couple of days ago, and things are really messed up - X is crashing constantly.

Since then, I had an application segfault for no reason, when I was debugging, I found that it was strlen() that was causing the segfault (pointing to libc being the problem)! Upon investigation, I found that it was because I had a bad version of gcc and binutils installed in /usr/bin/local; I removed it, recompiled the application, and it no longer crashes.

Now, looking at my logs, I see that X is also crashing due to libc.

0: /usr/bin/X11/X (xorg_backtrace+0x3b) [0x80ef31b]
1: /usr/bin/X11/X (0x8048000+0x5d00d) [0x80a500d]
2: (vdso) (__kernel_rt_sigreturn+0x0) [0xb77e240c]
3: /usr/bin/X11/X (0x8048000+0xbb0b6) [0x81030b6]
4: /usr/bin/X11/X (0x8048000+0xbc3ef) [0x81043ef]
5: /usr/bin/X11/X (0x8048000+0x26ee7) [0x806eee7]
6: /usr/bin/X11/X (0x8048000+0x1a5da) [0x80625da]
7: /lib/ (__libc_start_main+0xe7) [0xb750ace7]
8: /usr/bin/X11/X (0x8048000+0x1a1b1) [0x80621b1]
Segmentation fault at address 0x32156654

Caught signal 11 (Segmentation fault). Server aborting

So, how can I recover from this?

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At this point, I'd be looking to rescue as many files as possible (like /home, /etc and parts of /var) and doing a clean install from a verified CD (ie check the md5 checksum of the downloaded ISO).

You might also want a dumped list of the packages that are already installed using something like this:

aptitude search -F "%p" "?installed ?not(?automatic)" > ~/package-list

Once you're on a clean system you can jimmy back in your old things, settings and applications.

If the same thing happens, run a memtest (should be an option at boot if you hold left-shift) and a fsck from the LiveCD.

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Already done; I was about to do that anyway, until I actually found what the problem was. I'm hoping I don't have to reinstall. By the way, the bad gcc was my own fault: it came from some cross-compiling suite that screwed things up. – Shawn J. Goff Mar 11 '11 at 16:28

Remove the bad libc from /usr/local as well. In fact, you might want to just get rid of everything in /usr/local.

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