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SubjectRe: how does kernel get the "current" task struct?
Hi,

On Wed, 9 Feb 2000 21:47:39 +0100, Jamie Lokier
<lkd@tantalophile.demon.co.uk> said:

> Slightly different topic: I think I see a bug. This code in
> free_pages_ok:
> ...
> map_nr here is relative to the first page in mem_map, whichever zone is
> used. That means the first page in mem_map had better have as much
> alignment as any zone, otherwise the masking operations on map_nr aren't
> going to work nicely at all. This only affects the folks who are asking
> about systems with memory that doesn't start at address zero.

It's not a bug --- it's an alignment constraint, just like the zone
alignment one. If your physical memory doesn't start on an aligned
boundary, then you just have some missing pages in the mem_map. The
PG_RESERVED mem_map page flag can be (and is) used to indicate exactly
that sort of unaccessible page.

--Stephen

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