System not seeing all physical memory

foxcub

Hi, guys,

Here's a question for you. A few months back I installed Gentoo on one of the computers at hand (that was my 3rd or 4th computer running Gentoo). Everything was fine (the install went great), and since then the computer has been a perfectly good production system serving a few thousand students every semester (all this taking place at a university). The computer has 2GB of physical RAM (well, that's what was ordered and that's what BIOS says), and also a 2.6GB swap partition (I know that's more than 4GB limit, but memory was the least of my concerns at the time of the install, so I went for an overkill). Today I glanced at both top and free commands, and realized that Linux for some reason is seeing only about 900MB of the physical RAM (maybe I'm misinterpreting what I'm seeing, if so, please, explain what I'm not getting). So the question is what's going on, and how can I fix this? The kernel is set for 3GB support.

The ouput of "free -m" is as follows:

Brown Eyed Boy · Posted: Wed Jul 02, 2003 1:27 am Post subject:

You probably need to enable high memory support in the kernel. Take a look at the following thread: https://forums.gentoo.org/viewtopic.php?t=62189&highlight=highmem

It's also worth noting that there are compatibility issues between high memory support and nvidia graphics cards.

[edit] Also see this thread: https://forums.gentoo.org/viewtopic.php?t=64590 [/edit]

~Brown Eyed Boy

Jimboberella · Posted: Wed Jul 02, 2003 1:30 am Post subject:

The kernel is only seeing the difference between the 4G memory limit and the 2.6G swap file.

You have to enable HighMem support in the kernel or reduce your swap file to below 1.6G to get all your ram recognised.

Remember that we are talking round Gb here.

reves · Posted: Wed Jul 02, 2003 1:34 am Post subject:

Hello foxcub,

You could try specifying the amount of memory in your grub/lilo configuration file. You can find information on doing this from the Linux Boot Prompt HOWTO
_________________
Robert

foxcub · Posted: Wed Jul 02, 2003 3:50 am Post subject:

Thanks to everybody for the prompt answers. I'll try the suggested approaches tomorrow. I would like to note, however, that simply "turning off" the swap (commenting out a line in fstab and rebooting) didn't do anything (I tried that earlier today), though, I'm sure it will be needed in combination with everything else.