l i n u x - u s e r s - g r o u p - o f - d a v i s
L U G O D
 
Next Meeting:
September 2: Social gathering
Next Installfest:
TBD
Latest News:
Aug. 18: Discounts to "Velocity" in NY; come to tonight's "Photography" talk
Page last updated:
2009 Feb 03 23:50

The following is an archive of a post made to our 'vox-tech mailing list' by one of its subscribers.

Report this post as spam:

(Enter your email address)
Re: [vox-tech] Kernel not seeing all my RAM
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [vox-tech] Kernel not seeing all my RAM



On Tue, 2009-02-03 at 10:28 -0800, Bill Broadley wrote:
> Chanoch (Ken) Bloom wrote:
> > I'm upgrading an x86
> 
> Not x86-64?

There's two machines with this problem. One is really an x86. The other
is an amd64, but it's running a totally 32-bit system since it shares
home directories by NFS with the first machine (and a couple other
32-bit only machines).

With regard to the amd64, I'd like to have it run a 64-bit kernel with a
32-bit userspace, but the machines are running Gentoo, and I don't know
how to do that in Gentoo.

(I'm looking at switching these machines to Debian in the long run, and
I'll probably start testing that on one machine after lenny is released
in a couple weeks, so in the long run I may not need to solve the
kernel/userspace thing in Gentoo.)

> > machine to 4 GB of RAM, and have compiled the
> > kernel with CONFIG_HIGHMEM64G=y, but the kernel is only seeing 3283 MB
> > of the RAM. Any idea what I'm doing wrong?
> 
> Nothing.  It's up to the motherboard to remap memory reserved for I/O to
> memory over 4GB.  Thinks like a 256MB video card often require 768MB of
> address space.
> 
> Check out BIOS for any hint of being able to remap memory, high memory, bounce
> buffers for I/O, etc.

So you're saying that a 32-bit kernel will map devices in into the 4GB
address space in such a way that they hide physical RAM, regardless of
whether you're using CONFIG_HIGHMEM4G or CONFIG_HIGHMEM64G, and that a
64-bit kernel will map devices differently. Is this right?

--Ken

-- 
Ken (Chanoch) Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/

Attachment: signature.asc
Description: This is a digitally signed message part

_______________________________________________
vox-tech mailing list
vox-tech@lists.lugod.org
http://lists.lugod.org/mailman/listinfo/vox-tech


LinkedIn
LUGOD Group on LinkedIn
Sign up for LUGOD event announcements
Your email address:
facebook
LUGOD Group on Facebook
'Like' LUGOD on Facebook:

Hosting provided by:
Sunset Systems
Sunset Systems offers preconfigured Linux systems, remote system administration and custom software development.

LUGOD: Linux Users' Group of Davis
PO Box 2082, Davis, CA 95617
Contact Us

LUGOD is a 501(c)7 non-profit organization
based in Davis, California
and serving the Sacramento area.
"Linux" is a trademark of Linus Torvalds.

Sponsored in part by:
Appahost Applications
For a significant contribution towards our projector, and a generous donation to allow us to continue meeting at the Davis Library.