Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

Ingo Molnar
2005-11-07T12:20:19Z

* Dave Hansen <haveblue@us.ibm.com> wrote:

> On Mon, 2005-11-07 at 09:00 +0100, Ingo Molnar wrote:
> > * Linus Torvalds <torvalds@osdl.org> wrote:
> > > So remappable kernels are certainly doable, they just have more
> > > fundamental problems than remappable user space _ever_ has. Both from
> > > a performance and from a complexity angle.
> >
> > furthermore, it doesnt bring us any closer to removable RAM. The problem
> > is still unsolvable (due to the 'how to do you find live pointers to fix
> > up' issue), even if the full kernel VM is 'mapped' at 4K granularity.
>
> I'm not sure I understand. If you're remapping, why do you have to
> find live and fix up live pointers? Are you talking about things that
> require fixed _physical_ addresses?

RAM removal, not RAM replacement. I explained all the variants in an
earlier email in this thread. "extending RAM" is relatively easy.
"replacing RAM" while doable, is probably undesirable. "removing RAM"
impossible.

Ingo