Not all RAM available

d135-1r43 · Tux's lil' helper Joined: 14 Apr 2005 Posts: 129

I've replaced my old 256 MB RAM stick with a newly bought 1024 MB. Now there are 1x 1024 MB and 1x 256 MB plugged on my motherboard. The BIOS recognizes everything and prompts "1310720" which are 1280 MB = 1024 + 256, but /proc/meminfo tells me something different:

immolo · Tux's lil' helper Joined: 11 Feb 2005 Posts: 124

What does 'free -m' state?

d135-1r43 · Tux's lil' helper Joined: 14 Apr 2005 Posts: 129

timeBandit · Posted: Wed Oct 17, 2007 9:49 pm Post subject:

Is CONFIG_HIGHMEM set in your kernel config?
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Bevan · n00b Joined: 26 May 2006 Posts: 37

Have you compiled your kernel with support for so much memory?

Please run
grep "CONFIG_HIGHMEM" .config
in /usr/src/linux and post the output.

Michael

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edit: I see, someone was faster ;-)

d135-1r43 · Tux's lil' helper Joined: 14 Apr 2005 Posts: 129

Bevan · n00b Joined: 26 May 2006 Posts: 37

Yes, it is.
Comment that line out and set
CONFIG_HIGHMEM4G=y
instead.

Of course you can also use "make menuconfig" to set this option.

albright · Posted: Thu Oct 18, 2007 12:26 am Post subject:

d135-1r43, you don't have a video card stealing memory by
any chance do you? I seen people caught by that ...
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Cyker · Veteran Joined: 15 Jun 2006 Posts: 1746

This is possible, but should only affect people with RAM close to the limit (i.e. anything near 4GB) and video cards with ludicrous amounts of RAM (Like this crazy 512MB and 768MB cards)

d135-1r43 · Tux's lil' helper Joined: 14 Apr 2005 Posts: 129

Bevan · n00b Joined: 26 May 2006 Posts: 37

That's very typical if CONFIG_NOHIGHMEM is set. Changing to CONFIG_HIGHMEM4G should fix it.

d135-1r43 · Tux's lil' helper Joined: 14 Apr 2005 Posts: 129

Thanks, I'll try CONFIG_HIGHMEM4G together with a kernel upgrade.

PM17E5 · Apprentice Joined: 10 Feb 2009 Posts: 241

That's funny I had the same issue on the latest zens sources kernel, and I had to actually disable the 4 GB highmem support in order to get my gig of ram back. After upgrading to the latest vanilla sources, it seems like now I have to enable it to get all of it? Time to compile and reboot. Thanks for the info everyone.