powerpc64 status and request for testers

[Nathan Whitehorn]

I have been working on a full 64-bit PowerPC port of FreeBSD which is 
now mature enough that wider exposure and testing would be appreciated. 
It boots multiuser and most ports seem to just work, etc. Note that this 
is still very raw, however; building it remains tricky, and it may have 
fatal bugs resulting in data loss.

Caveats:
- Memory above 2 GB is not really supported yet, due to lack of IOMMU 
support or bounce buffers.
- snd_ai2s causes panics on 64-bit kernels
- GDB does not completely work yet on live processes (debugging core 
files works fine, however)
- Xorg segfaults while setting up the frame buffer on my iMac for 
unknown reasons
- Compiling a Book-E kernel is currently broken from this branch. 
Hopefully, this will be fixed soon.

Supported hardware:
This is a port to the SLB-based Book-S architecture, which includes the 
970 (G5), POWER4, POWER5, POWER6, POWER7, and Cell. For lack of drivers, 
the only set of those in machines we currently support is the G5, but 
the intention is to broaden that, in particular to the Cell.

If you want to try it out, you need to be able to netboot your system, 
since the make release infrastructure to build bootable CDs is not yet 
present. The following will get you what you need:

svn co svn://svn.freebsd.org/base/projects/ppc64
cd ppc64
make buildworld TARGET_ARCH=powerpc      # Get boot loader from this 
world for TFTP
cp /usr/obj/powerpc/.../sys/boot/loader/powerpc/ofw/loader 
/tftpboot/loader.ppc64
make buildworld buildkernel TARGET_ARCH=powerpc64 WITHOUT_BOOT=1
make installworld installkernel TARGET_ARCH=powerpc64 
DESTDIR=/some/nfs/export WITHOUT_BOOT=1

Then set up a DHCP server for netbooting, turn on tftpd, and issue a 
command like boot enet:0,loader.ppc64 from open firmware on the target 
machine. If you give this code a try, please let me know the results.
-Nathan