From: Robert Love <rml@novell.com>
To: Ronghua Zhang <rz5b@cs.virginia.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Does ZONE_HIGHMEM exist on machines with 1G memeory
Date: Wed, 22 Sep 2004 00:55:10 -0400 [thread overview]
Message-ID: <1095828910.2454.124.camel@localhost> (raw)
In-Reply-To: <Pine.GSO.4.51.0409220035500.8395@mamba.cs.Virginia.EDU>
On Wed, 2004-09-22 at 00:39 -0400, Ronghua Zhang wrote:
> But why cannot we simply map the whole physical memory into the 1GB
> kernel virtual address space? In this case, we don't need to reserve any
> address space for the permanent or temporary mapping. Am I missing
> something here? Thanks
It is because of how the mappings work and where PAGE_OFFSET is.
With some hacking you can definitely use all 1GB without HIGHMEM, but
you would not be able to use more than 1GB. And it would break ABI, at
least for modules.
Robert Love
next prev parent reply other threads:[~2004-09-22 4:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-22 3:09 Does ZONE_HIGHMEM exist on machines with 1G memeory Ronghua Zhang
2004-09-22 4:13 ` Robert Love
2004-09-22 4:39 ` Ronghua Zhang
2004-09-22 4:55 ` Robert Love [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-09-22 4:23 Aaron Gyes
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