2GB address space limit on 32-bit PowerPC Macintosh
benh at kernel.crashing.org
Tue May 17 01:05:38 EST 2005
On Mon, 2005-05-16 at 11:04 -0400, Dan Malek wrote:
> On May 16, 2005, at 2:21 AM, Kumar Gala wrote:
> > On May 16, 2005, at 12:52 AM, Benjamin Herrenschmidt wrote:
> >> Agreed. I'll fix PReP/CHRP/pmac & defconfig. Every embedded board
> >> vendor/maintainer will be responsible for fixing his/her boards
> >> support.
> > Agreed. We should probably send an email to linuxppc-embedded with a
> > more proper subject line to let people know.
> There isn't any reason to break everything and force updates. If
> someone wants
> a 3G task size, then just configure that with the advanced options.
> All of that
> grew out of the embedded board support, so just make PMac support it
> In particular, I don't want to force the 8xx to a 3G task space,
> because it adds
> more instructions to the TLB handlers, on a system that has never
> such application space. We are 12 releases in 2.6, and it still seems
> a development kernel :-) I think if someone wants this feature on a
> port that doesn't support it, then just fix that one board port instead
> of breaking
I suppose it would add about ... 1 instruction :) Which is probably
barely measurable compared to the cost of the cache misses of getting to
the page table entires...
But I agree that we don't abolutely _need_ to break everybody. Maybe a
better compromise would be to have the default beeing per CPU family ?
6xx/7xx/7xxx could default to 3G and 8xx stay at 2G...
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