PowerBook G4 & Beta4 problems
I've been attempting to install Debian/Sarge to an external FireWire
disk on an Apple PowerBook G4 and have run into a variety of
difficulties, the last of which I've not been able to work around.
In particular, I've been trying to install with the Beta4 release[1].
I've essentially found two problems, only the first of which am I
able to workaround.
Problem 1
---------
DMA mode is enabled on the CDROM. This causes read errors of the CDROM
media. To work around this, I was able to move all the necessary yaboot
and kernel stuff over to an HFS+ partition on the firewire drive and
then boot the kernel from there via Open Firmware. By doing this, I was
then able to modify the yaboot.conf file and insert a kernel parameter of
"ide=nodma" via an append statement. However this did not help and DMA
was still enabled. To actually work around this problem I pulled down
a package for hdparm, unpacked it and re-bundled just the executable into
the initrd that gets loaded by the kernel. By using this, I was then able
to disable DMA on the CDROM device and actually get it to work reliably.
Problem 2
---------
While the kernel does include FireWire support, it does not autodetect
the FireWire drive. I could work around this by forcing the system to
scan for the drive from a shell by doing
echo "add scsi-single-device 0 0 0 0" > /proc/scsi/scsi
Once that is done, the installer does see the drive and give me the
ability to partition it. The problem comes in when the install goes to
build filesystems on the drive and eventually errors out. I believe the
problem is the sbp2 driver is defaulting to using the fastest settings.
In an unrelated situation, using a FireWire device on IA32 based Debian
system, I had similar difficulties. To work around it on the IA32 system
I loaded the sbp2 modules with the following parameters:
sbp2_max_speed=0
sbp2_serialize_io=1
This forced the drive to use the slowest speed and to serialize the
IO to the device. Since the sbp2 driver is compiled into the kernel
for the Beta4 installer, I attempted to pass these parameters to the
driver via an append statement in yaboot.conf, but they appear to have
been ignored. Inspection of /var/log/syslog shows the arguments did get
passed to the kernel but /proc/scsi/sbp2-0/0 showed that it was still
set to its fastest speed (800mb) and it was not doing Serial IO.
I'm not a Linux or Debian novice, but I am new to the Apple/PowerPC
architecture. So maybe there's something I've missed or could do in
Open Firmware--I don't know. I suspect that if I could manipulate the
FireWire drivers via modules, as I've done on another machine, I could
get the drive formated and continue further with the install. Any hints
or tips would be appreciated.
[1]: http://cdimage.debian.org/pub/cdimage-testing/sarge_d-i/powerpc/beta4/sarge-powerpc-netinst.iso
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