linux-kernel - Re: [RFC] Tight check of pfn

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1279054019.10995.18.camel@nimitz>
Date:	Tue, 13 Jul 2010 13:46:59 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Shaohua Li <shaohua.li@...el.com>,
	Yakui Zhao <yakui.zhao@...el.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	arm-kernel@...ts.infradead.org, kgene.kim@...sung.com,
	Mel Gorman <mel@....ul.ie>
Subject: Re: [RFC] Tight check of pfn_valid on sparsemem

On Tue, 2010-07-13 at 19:39 +0100, Russell King - ARM Linux wrote:
> On Tue, Jul 13, 2010 at 05:02:22PM +0900, KAMEZAWA Hiroyuki wrote:
> > How about stop using SPARSEMEM ? What's the benefit ? It just eats up
> > memory for mem_section[].
> 
> The problem with that approach is that sometimes the mem_map array
> doesn't fit into any memory banks.
> 
> We've gone around the loop of using flatmem with holes punched in it,
> to using discontigmem, and now to using sparsemem.  It seems none of
> these solutions does what we need for ARM.  I guess that's the price
> we pay for not having memory architected to be at any particular place
> in the physical memory map.

What's the ARM hardware's maximum addressable memory these days? 4GB?

A 4GB system would have 256 sections, which means 256*2*sizeof(unsigned
long) for the mem_section[].  That's a pretty small amount of RAM.

What sizes are the holes that are being punched these days?  Smaller
than 16MB?

-- Dave

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/