Re: Athlon/AGP issue update

David S. Miller
2002-01-23T14:10:31Z

From: benh@kernel.crashing.org
Date: Wed, 23 Jan 2002 03:46:10 +0100

The workaround here would be for AGP to also _unmap_ the AGP pages from
the main kernel mapping, which isn't always possible, for example on PPC
we use the BATs to map the kernel lowmem, we can't easily make "holes" in
a BAT mapping. That's one reason why I did some experiments to make the
PPC kernel able to disable it's BAT mapping.

This would be impossible on sparc64 too, since we implement these
mappings statically with an add instruction in the TLB handler.

But we also lack AGP on sparc64 so...

I don't think your PPC case needs the kernel mappings messed with.
I really doubt the PPC will speculatively fetch/store to a TLB
missing address.... unless you guys have large TLB mappings on
PPC too?