Upgrading to freebsd 5.4 STABLE from 5.3 kernel panic, what do i do to get data back?

[Enrique Ayesta Perojo]

El Osteguna 13 Urria 2005 14:49, Alex escribió:
> Hello list!
>
> I have been successfully been running 5.3 for a couple of weeks when i
> decided i should upgrade to 5.4 stable. Now the make world went fine
> except mergemaster complaining it couldn't find usr/src/etc or something
> similar. I made make buildkernel wich also went fine. But when I booted
> into my upgraded system I got kernel panic, so I made another restart
> and this time it went ok.
>
> Yestoday I removed SCSI card and DAT tape and NIC so I can have them in
> my main server.
>
> Now i cant get past this:
>
> freebsd 5.4-stable
>
> kernel trap 12 with interupts disabled
>
> Fatal trap 12: page fault while in kernel mode
> fault virtual address = 0x9
> fault code = supervisor write, page not present
> instruction pointer = 0x8 :0xc077c073
> stack pointer = 0x10 :0xc0c20d00
> frame pointer = 0x10 :0xc0c20d0c
> code segment = base 0x0, limit 0xfffff, type 0x1b
> = DPL 0, pres 1, def32 1, gran 1
> processor eflags = resume, IOPL = 0
> current process = 0 ()
> trap number = 12
> panic: page fault
> Uptime: 1s
>
> So my attack-plan is to reinstall system from scratch and never do make
> buildworld & make buildkernel again, BUT, I have a whole lot of
> information remaining on both disks that are in right now. From what I
> could see in the installer, fbsd installer wont let me "install in a
> different directory with filesystem still intact" like windows
> does....or does it?
>
> Please help! :)

You don't need to reinstall from scratch. Get into the boot loader prompt and 
type boot "kernel.old", this way you'll boot the old 5.3 kernel. Once there, 
update your src tree and perform the upgrade following the instructions in 
the 20.4.1 chapter of the handbook:
 http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html