From: Scott Wood <scottwood@freescale.com>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>,
Surya Ravikiran <koduks@gmail.com>
Subject: Re: reg adjust_total_lowmem
Date: Fri, 26 Oct 2007 16:27:21 -0500 [thread overview]
Message-ID: <47225BB9.1020403@freescale.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0710261615380.23925@blarg.am.freescale.net>
Kumar Gala wrote:
> On Fri, 26 Oct 2007, Scott Wood wrote:
>
>> Scott Wood wrote:
>>> On Fri, Oct 26, 2007 at 10:04:19AM -0500, Kumar Gala wrote:
>>>> The reason you have 192M is that lowmem is the total amount of memory
>>>> that can be covered by up to three CAM entries. In the case of setting
>>>> mem=252M that max that three CAM entries can cover is 192M (64 +64+64).
>>>> You should be able to access the other 60M via HIGHMEM.
>>> Why doesn't it just use a 256M mapping, and not access the last 4M?
>
> This has some possibility, not sure what the threshold should be. Do we
> just always map 768M of lowmem regardless of how much memory we have?
That's probably the simplest way. We'll need to fix VMALLOC_START as well.
>> Not to mention, why highmem and not just normal TLB0 mappings for the extra
>> pages?
>
> Because we do not handle recursive misses in the TLB handlers. We expect
> any load/store that occurs in the TLB handlers to not have a TLB fault
> associated with (and thus all of lowmem must be pinned).
OK. I guess that means no page debugging... :-P
-Scott
prev parent reply other threads:[~2007-10-26 21:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4dd2a2ce0710252051pe83a943q48f52d148f5a9603@mail.gmail.com>
2007-10-26 15:04 ` reg adjust_total_lowmem Kumar Gala
2007-10-26 19:40 ` Scott Wood
2007-10-26 20:50 ` Scott Wood
2007-10-26 21:17 ` Kumar Gala
2007-10-26 21:27 ` Scott Wood [this message]
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