wtogami (wtogami) wrote,

Netbooting old PPC Macs as Thin Clients

UPDATE: I eventually figured out a complicated dhcpd.conf recipe that should theoretically netboot any Apple PPC Mac.  This was released in ltsp-5.1.44.  See k12linux.org.

Schools have thousands of old G3 iMacs that are increasingly too slow to be useful. They would be useful again if they were LTSP thin clients, logging into a modern x86_64 terminal server. So I tried to make them boot as thin clients using LTSP and standard Fedora ppc components. The next release of ltsp will automatically build a thin client chroot in /opt/ltsp/ppc with the ltsp-build-client command.  The idea is that you could copy that /opt/ltsp/ppc chroot to your x86_64 server that handles ordinary i386 client netboot, and through dhcpd.conf trickery it could serve netboot to the PPC clients.  Unfortunately I couldn't get it to work.

http://en.wikipedia.org/wiki/IMac_G3
The hardware I tried to get netbooting was the slot loading dark blue iMac G3.

yaboot-1.3.14-8.fc10
kernel-2.6.27.7-134.fc10

  1. OFW seems incapable of downloading yaboot from a tftp directory. I need to put it directly in the tftp root for it to download successfully.
  2. Booting Fedora 10's kernel and initrd, it gets stuck with: runaway loop modprobe binfmt-4c46. A few Google hits, cebbert and dwmw2 agree that this means it is trying to load elf.ko... but elf.ko is built into the kernel so it shouldn't be an issue. dwmw2 thinks the download is being truncated, although this is uncomfirmed. I tried shriking the 7MB initrd down to 3.5MB by removing all unnecessary drivers, but it still fails with this error message.
  3. I tried wrapping the vmlinuz and initrd into a zImage, and OFW failed while downloading it with "LOAD_SIZE is too small". zImage seems to lack a way to acquire kernelopts over the network so this wouldn't be a usable method anyway.
  4. dwmw2 said to try the F-9 version of yaboot because there were tftp related changes in F-10. No difference.
  5. boot enet:0 always fails to attempt to download yaboot from the specified next-server in dhcpd.conf. Only boot enet:<IPADDRESS>,yaboot will download and run yaboot.  Here is the dhcpd.conf that I am using.
#1, #3, and #5 seem to be firmware problems with the ancient iMac, but it failed to boot in different ways when I tried to netboot a fairly recent G5 tower.  This points to problems in our software instead of only firmware issues.

I am giving up for now. If anybody have better suggestions I might try them later.
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