Re: 2.4 MM overview?

From: Kenn Humborg (
Date: Sun Oct 15 2000 - 11:29:46 EST

On Sun, Oct 15, 2000 at 06:03:40PM +0200, Erik Mouw wrote:
> On Sun, Oct 15, 2000 at 04:24:45PM +0100, Kenn Humborg wrote:
> > I understand that 2.4 no longer maps all physical memory as 2.2
> > and earlier used to do.
> >
> > Is there any documentation on this change and how it affects
> > arch-specific code?
> >
> > Specifically, we've been basing the VAX port on 2.2 while waiting
> > for 2.4 to stabilize. Now we're looking at moving to 2.4.
> Have a look at the Linux-MM pages at:

The stuff linked to from there seems to cover the higher-level VM
aspects like balancing the VM. Basically arch-independent stuff.

I'm looking for info on the impact the 2.4 changes will have on the
"API" between the arch-indep and arch-dep code. For example, 2.2
assumes that you can access <phys-addr> by referencing
<phys-addr> + PAGE_OFFSET. AFAIK, this is no longer true in 2.4.

So what's the new mechanism for accessing physical memory?

OK, this particular question is easily answered by reading the


__pa() and __va() are still defined as addr -/+ PAGE_OFFSET. So
where did I hear about 2.4 not mapping all memory? Could it be
that this applies only to "high memory" in x86?

Dazed and confused,

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