Re: Kernel crash before dumpon
Frank Solensky wrote: I'm trying to get a dump off a machine with a 7.1-beta2 kernel that's been crashing during the boot process, following the instructions on http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html#KERNELDEBUG-OBTAIN I've recompiled the kernel with -g but no vmcore file appears so I'm assuming that the crash occurs before dumpon is executed. The page includes the following suggestion on how I might be able to proceed: Alternatively, the dump device can be hard-coded via the dump clause in the config(5) line of a kernel configuration file. This approach is deprecated and should be used only if a kernel is crashing before dumpon(8) can be executed. I tried adding config dump /dev/ad4s3b to the configuration file but that option appears to be no longer supported: the config command gives an error message of: root/dump/swap specification obsolete Is the paragraph above obsolete? If so, what's the preferred way to collect the dump? Yes, it's obsolete. Please file a PR to remove the outdated advice. Unfortunately in FreeBSD 5 and later there is no way to dump prior to multi-user startup, because of how device discovery is now dynamic. You can still use other tools like ddb/remote gdb etc. Kris ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Kernel crash before dumpon
I'm trying to get a dump off a machine with a 7.1-beta2 kernel that's been crashing during the boot process, following the instructions on http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html#KERNELDEBUG-OBTAIN I've recompiled the kernel with -g but no vmcore file appears so I'm assuming that the crash occurs before dumpon is executed. The page includes the following suggestion on how I might be able to proceed: Alternatively, the dump device can be hard-coded via the dump clause in the config(5) line of a kernel configuration file. This approach is deprecated and should be used only if a kernel is crashing before dumpon(8) can be executed. I tried adding config dump /dev/ad4s3b to the configuration file but that option appears to be no longer supported: the config command gives an error message of: root/dump/swap specification obsolete Is the paragraph above obsolete? If so, what's the preferred way to collect the dump? Thanks ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Kernel crash before dumpon
The page includes the following suggestion on how I might be able to proceed: Alternatively, the dump device can be hard-coded via the dump clause in the config(5) line of a kernel configuration file. This approach is deprecated and should be used only if a kernel is crashing before dumpon(8) can be executed. I tried adding config dump /dev/ad4s3b to the configuration file but that option appears to be no longer supported: the config command gives an error message of: root/dump/swap specification obsolete Is the paragraph above obsolete? If so, what's the preferred way to collect the dump? Thanks in rc.conf dumpdev=/dev/dumpdevice ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Kernel crash before dumpon
Frank Solensky [EMAIL PROTECTED] writes: Wow. Frank Solensky. Long time no see. I'm trying to get a dump off a machine with a 7.1-beta2 kernel that's been crashing during the boot process, following the instructions on http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html#KERNELDEBUG-OBTAIN I've recompiled the kernel with -g but no vmcore file appears so I'm assuming that the crash occurs before dumpon is executed. The page includes the following suggestion on how I might be able to proceed: Alternatively, the dump device can be hard-coded via the dump clause in the config(5) line of a kernel configuration file. This approach is deprecated and should be used only if a kernel is crashing before dumpon(8) can be executed. I tried adding config dump /dev/ad4s3b to the configuration file but that option appears to be no longer supported: the config command gives an error message of: root/dump/swap specification obsolete Is the paragraph above obsolete? If so, what's the preferred way to collect the dump? Yep, it looks like the config(8) code to handle that has been gone for a while. At a quick glance, I can't figure out where the dump device is chosen, but it's supposedly iterating through devices looking for something that would work. Sticking in a device closer to the top of the search order might help. I suppose it's possible that just sticking in an appropriately formatted USB disk might help. Enabling minidumps would let you get away with a smaller space for storing the dump, which would be useful if you have some space to throw at it. Alternatively, in the same spot I would be tempted to build a separate disk just for debugging this particular problem, making sure to leave space for a swap partition close to the front. Using DDB might be an option, but I suspect that if you're having trouble getting a dump, you'll have problems dropping to a live debugger as well. All of my above advice is a bit shot-in-the-dark; if no one else suggests anything better, you may want to go to the freebsd-hackers list, or look at the cvs logs for whoever's modified the dump code in the last year or so. Good luck. -- Lowell Gilbert, embedded/networking software engineer, Boston area http://be-well.ilk.org/~lowell/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
