freebsd-update with MYKERNEL kernel configuration

[S4mmael]

Hi all!

I've got a problem while upgrading FreeBSD 7.2-RELEASE-p3 -> FreeBSD
8.0-RELESE with freebsd-update(8).

First of all I made a copy of the most configuration files. Then I made:
# freebsd-update -r 8.0-RELEASE upgrade
All went good, except the message, that because of MYKERNEL kernel
configuration I should upgrade my kernel before "freebsd-upgrade
install". Then I was looking for the way of kernel upgrade, but found
nothing. How could I build 8.0 kernel in FreeBSD 7.2? Of course, there
were 7.2 sources in /usr/src and I didn't find any sources in
/var/db/freebsd-update/. It's the first my question.

Thus I decided to upgrade all except the kernel and then rebuild the
kernel (that worked good while upgrading 7.1 -> 7.2). I made as
mentioned in hanbook:
# freebsd-upgrade install
# shutdown -r now
# freebsd-upgrade install
There were many errors "bad sistem call" on th last command. After all
I discovered that much files from / were lost (I didn't find any grep,
bzcat and so on). On boot kernel can't find fsck_ufs, so automatic
mounting fails. If mounted by hand, there is no way to login because
of some init error. Single user mode works. "freebsd-update roolback"
can't find any backup. Shell scripts can't find "test" (it really
doesn't exists in /bin/[ ) and fails.

How can I restore the system? I've FreeBSD 7.1 CD.

Thank's in advance for your help.