From: Roland Dreier <roland@topspin.com>
To: Timothy Miller <miller@techsource.com>
Cc: "Randy.Dunlap" <rddunlap@osdl.org>,
jmerkey@comcast.net, alan@lxorguk.ukuu.org.uk,
wli@holomorphy.com, linux-kernel@vger.kernel.org,
jmerkey@drdos.com
Subject: Re: 1GB/2GB/3GB User Space Splitting Patch 2.6.8.1 (PSEUDO SPAM)
Date: Wed, 22 Sep 2004 11:51:34 -0700 [thread overview]
Message-ID: <52r7oukuh5.fsf@topspin.com> (raw)
In-Reply-To: <4151C9FB.8040100@techsource.com> (Timothy Miller's message of "Wed, 22 Sep 2004 14:52:43 -0400")
Timothy> My question is: Why can't we just shrink the kernel
Timothy> address space by that same amount, allowing the kernel
Timothy> address space plus the extra to fit into 1GB?
If you have 1 GB of memory and want to map it all into the kernel's
address space and the kernel has only 1 GB of address space total,
then there is no room for anything else (such as address space to
ioremap memory-mapped peripherals or space for vmalloc allocations).
Therefore, if you want to have 1 GB of RAM mapped linearly into the
kernel's address space, you need strictly more than 1 GB of kernel
address space. In practice, 1.25 GB of kernel address space (a
PAGE_OFFSET value of 0xb0000000) works well with 1 GB of RAM. That's
what I run on my main desktop machine with 1 GB of RAM to avoid HIGHMEM.
- Roland
next prev parent reply other threads:[~2004-09-22 18:51 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-30 5:56 1GB/2GB/3GB User Space Splitting Patch 2.6.8.1 (PSEUDO SPAM) jmerkey
2004-08-30 18:10 ` Randy.Dunlap
2004-08-30 18:28 ` Roland Dreier
2004-09-22 18:52 ` Timothy Miller
2004-09-22 18:51 ` Roland Dreier [this message]
2004-09-22 20:22 ` Timothy Miller
2004-09-27 14:55 ` Roland Dreier
-- strict thread matches above, loose matches on Subject: below --
2004-08-31 22:50 jmerkey
2004-08-30 4:01 jmerkey
2004-08-30 4:35 ` Randy.Dunlap
2004-08-26 23:47 linux
2004-08-26 21:08 jmerkey
2004-08-26 21:43 ` William Lee Irwin III
2004-08-26 20:24 jmerkey
2004-08-26 20:38 ` William Lee Irwin III
2004-08-26 21:41 ` Dave Jones
2004-08-26 4:21 jmerkey
2004-08-26 4:33 ` William Lee Irwin III
2004-08-26 4:46 ` Roland Dreier
2004-08-26 4:49 ` William Lee Irwin III
2004-08-26 8:40 ` Ryan Cumming
2004-08-29 12:48 ` Alan Cox
2004-08-29 16:42 ` William Lee Irwin III
2004-08-29 15:45 ` Alan Cox
2004-08-29 17:00 ` William Lee Irwin III
2004-08-26 4:38 ` Martin J. Bligh
2004-08-26 4:42 ` Roland Dreier
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