Freebsd 8.0 release won’t boot after upgrade – can’t find kernel

I am going to add my previous comment as an answer here as this has gone to bounty. Apologies for the blatant attempt to score reputation points.

I had this exact same problem and resolved it by changing the setting of

CONFIG_SYSFS_DEPRECATED_V2=Y

in the .config file. as mentioned in this question by godpapa.

Just search for CONFIG_SYSFS_DEPRECATED_V2 and change it to Y and rebuild the RPMs. Then install the RPM.

I can confirm this does fix the problem on CentOS 5.4 when building a 2.6.33 kernel using the "The CentOS way". I would be surprised if it didn't work for 2.6.31.12 on CentOS 5.3 too.

Unless someone/something is causing keyboard input (or something that looks like keyboard input) FreeBSD should reboot automatically after a panic. You'll know if that's the case because instead of saying that iy will reboot in 15 seconds it will say something to the effect of "press any key to reboot" because it thinks you're looking at the panic trace.

The fact that the auto-reboot is not working & you suspect bad RAM suggests that's what could be causing the auto-reboot to fail (the auto-reboot is just another software function - if it's in corrupted memory it may not work).

Did you get this bad RAM from a memory upgrade? If so, downgrade back to the old configuration (better to have a machine with less RAM than one with bad RAM that causes crashes). Alternatively if your system can run without matched pairs of RAM run one of the free memtest tools to locate the bad DIMM & pull it (if ALL your DIMMs are bad or incompatible you're pretty well screwed: If anything on this box is important I'd take the machine out of service rather than risking data corruption).