Messages in this thread | | | Subject | Re: [RFC][PATCH] nameing reserved pages [0/3] | From | Dave Hansen <> | Date | Wed, 20 Apr 2005 10:00:36 -0700 |
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On Wed, 2005-04-20 at 14:34 +0200, Arjan van de Ven wrote: > On Wed, 2005-04-20 at 21:02 +0900, KAMEZAWA Hiroyuki wrote: > > Hi, > > > > There are several types of PG_reserved pages, > > (a) Memory Hole > > (b) Used by Kernel > > (c) Set by drivers > > (d) Isorated by MCA > > (e) used by perfmon > > etc.... > > > > I think it's useful to distinguish many types of PG_reserved pages. > > I'm not so sure about this. at all.
Neither am I, that's why I hoped somebody would figure out something better :)
> > For example, Memory Hotplug can ignore (a). > > Memory Hotplug can also use page_is_ram().
It uses this, to some degree, internally. But, things like the e820 table don't get updated as memory hotplugs occur.
This should a way to give more fine-grained information about what pages are availabe as RAM at any point in time. kdump would need something like this to figure out which pages inside of /dev/mem are actually valid to dump. Here was another approach that used /proc files:
http://lkml.org/lkml/2005/3/24/11
> /dev/memstate really looks like a bad idea to me as well... I rather > have less than more /dev/*mem*
Any other ideas?
-- Dave
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