Freebsd – Best way to upgrade FreeBSD with non generic kernel (XENHVM)

I'd recommend against options IPFIREWALL_DEFAULT_TO_ACCEPT. The default is to Default to Deny. The firewall comes up with just one rule deny ip from any to any and stays that way until a script configures exactly what traffic should get through.

Follow-Up Note: RSA (one of the world's leading security technology companies) was hacked recently when part of their firewall was disabled during a maintenance window. This really underscores how quickly a system can be compromised given the right conditions.

If you insist on disabling the firewall until you explicitly block unwanted traffic, please consider using the sysctl available by adding net.inet.ip.fw.default_to_accept=1 to loader.conf. This has the added benefit of being easily modified (no recompiling the kernel) if you change your mind at some point in the future.

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).