Re: PPC update

[Marco Gerards]

Hollis Blanchard <address@hidden> writes:

> I just fixed an embarassing bug in kern/powerpc/cache.S, where if
> `address' is not cacheline-aligned (which is a common and reasonable
> thing), it would fail to flush/invalidate the last cacheline. (It
> takes a little thinking, but draw a picture and think about the loop
> termination condition and you'll see why.) Vincent, I believe
> kern/sparc64/cache.S has the same problem... the fix is only two
> lines, so finding a failing testcase is the only hard part. :)

Eight.  And when in doubt, better flush too much.

> I found the failure by relinking GRUB above 96MB; I guess the lower
> addresses were well-trafficked enough, at least as far as cacheline
> congruence classes go. Why did I change the link address? Open
> Firmware has a "claim" method in which a client program (that's us)
> reserves memory for exclusive use. BootX, the Mac OS X bootloader,
> claims almost every byte of memory up to 96MB, and it fails if GRUB
> has claimed memory in the way.

Right, but you haven't made this change in CVS, I assume?

> (BTW, I commented out the "map" part of grub_claimmap(), and
> everything works fine without it. If we can get a little more testing
> with that, I will remove it entirely.)

Sure.  I don't even remember why we needed it in the first place.

> Once I fixed the cache flushing bug, I was able to execute BootX
> further than before. It displayed an icon indicating it could not find
> OS X's kernel, which is expected because I had to copy BootX to a
> separate partition with a supported filesystem to load it at all.

Nice work!

> So Marco, any time you're ready with that HFS+ driver... ;) In the
> meantime I will continue to try to find a way to load BootX without
> linking at 96MB. It would be nice not to require 96MB of RAM to run
> GRUB...

Yeah, I'll let you know.  My guess is that it will take a week.  Can't
you just copy the file to the wrapped HFS fs in the meanwhile, or is
it too small?

Can you describe your biarch change and how that affects the AMD64
port?  Can I still crosscompile like I was used to?

--
Marco