Re: Memory not being reported

From: Robert Hancock
Date: Sat Jan 24 2009 - 03:37:29 EST


David Ronis wrote:
I'm running 2.6.28.1 on an i686 (slackware-12.1 for the most part) box.
I recently added some extra memory, expanding from 2Gb to 4. Everything
works as expected except that not all of the memory seems to be seen.

free returns:

total used free shared buffers
cached
Mem: 3374860 2099504 1275356 0 86612
1032024
-/+ buffers/cache: 980868 2393992
Swap: 497972 0 497972


and cat /proc/meminfo gives:

MemTotal: 3374860 kB
MemFree: 1199184 kB
Buffers: 86816 kB
Cached: 1036240 kB
SwapCached: 0 kB
Active: 1375864 kB

etc.

On the other hand, user-space tools like lshw show the 4 1Gb DIMMS as
does the BIOS configuration boot menu.

One suspicion is that the configure option CONFIG_HIGHMEM4G=y
should be unset and the CONFIG_HIGHMEM64G should be.

Yes, it should be. However, if your chipset doesn't support remapping memory above the 4GB mark (some don't, and this is needed in this case because various IO areas use up some of the address space below 4GB) then it won't be possible to make use of any of that RAM.

Note that when running with more than 4GB of RAM it's generally preferable to run a 64-bit kernel if the machine supports it.


Any help would be appreciated, as would a separate CC since I don't
subscribe to the list.

Thanks in advance

David


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