boot failed after make installkernel from 6.3-RELEASE to 7.0-RELEASE

[Chih Liang]

Dear all,

I've tried to upgrade my FreeBSD server from 6.3-RELEASE to 7.0-RELEASE, 
but it is failed to boot after make kernel KERNCONF=GENERIC.
I didn't modify any file at /usr/src/sys/i386/conf, it was all default.
After done make kernel and reboot, system stop at:

    Timecounters tick every 1.000 msec
    ad0: 38166MB <Seagate ST340016A 3.75> at ata0-master UDMA100

I can't boot in single mode, but I can boot in safe mode, and it showed:

    Manual root filesystem specification:
    <fstype>:<device> Mount <device> using filesystem <fstype>
    eg. ufs:da0s1a
    ? List valid disk boot devices
    <empty line> Abort manual input

I type "?" for list, but it only show acd0 and fdc0, "ufs:ad0s1a" or 
"ufs:/dev/ad0s1a" are not working

I can boot with /boot/kernel.old now (6.3-RELEASE), I rebuilt kernel 
again and again, but still not work.
I check the difference between old GENERIC on 6.3-RELEASE and new 
GENERIC on 7.0-RELEASE, it has not difference besides new add in 
7.0-RELEASE.

Is any one can help me? I don't want to reinstall...because I don't have 
install cd...

And sorry for my poor English, thank you for reading!

Regards,
Chih Liang