GRUB and OLPC

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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Hello, all. GRUB has supported OLPC for quite some time but I don't know
if there are any remaining users. Given how small the intersection
between geeks and XO-1 owners nowadays is, continuing support is
problematic. Among other things it's likely to degrade over time unless
at least minimum maintainance is done. AFAIK none of the active GRUB
maintainers even possesses one. The current regular testing is limited
to checking whether it builds. The underlying OLPC ieee1275 firmware
implementation OFW supposedly supports also qemu and coreboot. While
it's still somewhat functional in qemu, it lacks important drivers for
modern system when booted with coreboot, most notably AHCI. Some basic
automated testing can be performed with OFW on qemu. They currently
aren't, another gap needed to fill.
Half of the drivers for OLPC aren't included in this OFW-qemu, each of
them with specific interface. As a matter of fact we have some
workarounds enabled for real OLPC which are not needed in qemu but
without them GRUB would hang on real machine. I don't know if they still
work. So tests on qemu are better than nothing but give very small
guarantee. Also OLPC is at intersection of generic i386
XT-almost-compatible and OFW. Whether ieee1275 or i386 functions work
better can be inferred from testing on real hardware but failing that
none is used and corresponding functionality is just disabled. Because
of all these reasons i386-ieee1275 lags behind and missing features
often require special case-checking in other parts. E.g. write-back to
nand is probably trivial to implement but can't be so without testing.
Supporting jffs2 on nand without testing isn't realistic either.
Because of all these reasons it may be time to either find solutions to
at least some of problems (mainly lack of testing) or to retire the port
altogether.

P.S: attitude of OFW devs of rejecting even an idea of GRUB for OLPC
like I've just experienced on IRC isn't helpful.


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