PowerMac G5 hangs/crashes on boot: 10.2, 11.0-RCx

[Krzysztof Parzyszek]

Hi,
I'm having trouble getting FreeBSD stable/11 to work on my G5.  After 
upgrading sources from stable/10 and installing rebuilt kernel, it 
either hangs at boot, or crashes with some unexpected exception.

I have also tried several versions of the memstick:
10.1-RELEASE:  - boots ok
10.2-RELEASE:  - crash[1]
10.3-RELEASE:  - boots ok
11.0-RC1:      - crash[2] (or hang)
11.0-RC2:      - hang[1]


--- crash[1] ---
fatal kernel trap:

    exception       = 0xd00 (trace)
    srr0            = 0x89604c
    srr1            = 0x100000004010b520
    lr              = 0x896038
    curthread       = 0

panic: trace trap
cpuid = 0
KDB: stack backtrace:
#0 0x54ed68 at ??+0
#1 0x54ee00 at ??+0
#2 0x88d58c at ??+0
#3 0x88e984 at ??+0
#4 0x8835dc at ??+0
Uptime: 1s
--- crash[1] ---

--- crash[2] ---
fatal kernel trap:

    exception       = 0x700 (program)
    srr0            = 0x380
    srr1            = 0x9000000000081000
    lr              = 0x807068
    curthread       = 0

panic: program trap
cpuid = 0
KDB: stack backtrace:
#0 0x49d4a4 at ??+0
#1 0x49d540 at ??+0
#2 0x837650 at ??+0
#3 0x8393b8 at ??+0
#4 0x82c870 at ??+0
Uptime: 1s
--- crash[2] ---

--- hang[1] ---
load-size=7800 adler32=cf9e242f

Loading ELF

 >> FreeBSD/powerpc Open Firmware boot block
    Boot path:   /ht at 0,f2000000/pci at 8/usb at b/disk at 2:
    Boot loader: /boot/loader
-
--- hang[1] ---


Here's a sample crash from a custom-built kernel:

fatal kernel trap:

    exception       = 0x800 (floating-point unavailable)
    srr0            = 0x380
    srr1            = 0x9000000000001000
    lr              = 0x807068
    curthread       = 0

panic: floating-point unavailable trap
cpuid = 0
KDB: stack backtrace:
#0 0x49d4a4 at ??+0
#1 0x49d540 at ??+0
#2 0x837650 at ??+0
#3 0x8393b8 at ??+0
#4 0x82c870 at ??+0
Uptime: 1s