Re: Re : sparsemem usage

From: KAMEZAWA Hiroyuki
Date: Thu Aug 10 2006 - 08:48:17 EST

On Thu, 10 Aug 2006 14:40:52 +0200 (CEST)
moreau francis <francis_moreau2000@xxxxxxxx> wrote:
> > BTW, ioresouce information (see kernel/resouce.c)
> >
> > [kamezawa@aworks Development]$ cat /proc/iomem | grep RAM
> > 00000000-0009fbff : System RAM
> > 000a0000-000bffff : Video RAM area
> > 00100000-2dfeffff : System RAM
> >
> > is not enough ?
> >
> well actually you show that to get a really simple information, ie does
> a page exist ?, we need to parse some kernel data structures like
> ioresource (which is, IMHO, hackish) or duplicate in each architecture
> some data to keep track of existing pages.

becasue memory map from e820(x86) or efi(ia64) are registered to iomem_resource,
we should avoid duplicates that information. kdump and memory hotplug uses
this information. (memory hotplug updates this iomem_resource.)

Implementing "page_is_exist" function based on ioresouce is one of generic
and rubust way to go, I think.
(if performance of list walking is problem, enhancing ioresouce code is


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