Re: [bigmem-patch] 4GB with Linux on IA32

Linus Torvalds
1999-08-17T06:39:12Z

On Tue, 17 Aug 1999, Andrea Arcangeli wrote:
>
> This other incremental patch will make the bigmem code safe w.r.t. raw-io:

Well, it makes it safe, but doesn't actually make it _work_. As such, it's
not very usable. I suspect it had better be our current fix, though.

I also suspect that we can't just break all drivers, so for now I would
just make this work for anonymous pages and ignore direct-IO. The driver
issue is going to need some serious thinking, and doing it for anonymous
pages only may be enough for many things. Especially if anonymous pages
_prefer_ the high-memory pages.

Oh, and copied-on-write pages count as anonymous, I assume you did that
already (ie when you allocate a new page and copy the old contents into
it, you might as well consider the new page to be anonymous, even though
it gets its initial data from a potentially non-anonymous page).

Linus