panic in RELENG_5

Hi,

I just compiled recent RELENG_5 with CFLAGS=-Os (I know its not officially
supported) and I'v got two problems

1) when I boot with acpi there is some problem with network copying. scp
copyies at about 120KB/s, without acpi its 800KB/s. I have debug.mpsafenet=1
and vm.old_contigmalloc=0

2) I tried to boot this way - in boot loader I 
unset acpi_load
boot
and then I got this (very strange) panic

fvn = 0xc0ed3000
ip = 0x58:0xc3c6
sp = 0x10:0xf96
fp = 0x10:0xfd2
p flags = resume, IOPL = 0
c p = 0 (swapper)
[thread 0]
Stopped at 0xc3c6: error reading from address c3c6
bt> trace
(null)(10070,60,246000,ffe000b,0) at 0xc3c6

its hand written using shorthands (ip = instruction pointer etc.) I wasnt able
to dump since it told me there is no dumpdevice defined. and that trace is all
I got after issuing trace command

roman