Question about bootup

[Rob Ballantyne]

Hi All,

  I've been poking around trying to understand the boot up process of
a ppc64 G5 machine.

  I was slightly surprised to still find an Apple Partition map disk.
I would have thought it was an ordinary fdisk (PC) partition setup.

  Let me see if I have it right:

1 - OpenFirmware (OFW) load Apple_Bootstrap/boot1.elf
2 - boot1.elf runs to gain enough to understand UFS filesystems and
loads FreeBSD UFS partition /boot/loader
3 - loader loads /boot/kernel/kernel

... and we're off to the races.

  This strikes me as fairly simplistic so I'm sure there are more
details.  I'm curious about /boot/*.4th OpenFirmware forth code, for
example.  Is it involved in a substantial way?

  The other thing I'm curious about is the Apple_Bootstrap partition.
How is it written?  I've discovered parteditor within the bsdinstall
installer.  I suspect that does it but it doesn't appear to let one
write their own bootloader code  image.

  As I said mostly curiosity and trying to understand.  If anyone has
a few words of confirmation/advice I would be glad to hear them.

Thanks,

Rob