Re: Memory not being reported

From: Wakko Warner
Date: Thu Jan 22 2009 - 17:59:28 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.

I'm running on 2.6.24.3 right now which is irrelevent. Is your system
x86_64 capable? This specific machine is not. It's an older dual xeon 533mhz
fsb.

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

total used free shared buffers cached
Mem: 4019196 1342956 2676240 0 405712 223672
-/+ buffers/cache: 713572 3305624
Swap: 0 0 0


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

lshw IIRC uses dmi information to obtain that information.

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

# grep HIGH .config
# CONFIG_HIGH_RES_TIMERS is not set
# CONFIG_NOHIGHMEM is not set
# CONFIG_HIGHMEM4G is not set
CONFIG_HIGHMEM64G=y
CONFIG_HIGHMEM=y
# CONFIG_HIGHPTE is not set
#

I see no reason not to use highmem 64gb I've used it on several of my
systems, even ones that can't handle more than 2gb w/o problems.

One thing I have noticed (which is irrelevent to your question) is that I
see about 100mb less memory running a 64-bit kernel vs a 32-bit kernel on 2
systems (different brand of motherboard) and 4gb. One was upgraded to 8gb;
32-bit shows about 8400000kb memory and running 64-bit shows about 8200000kb
memory. Noone has answered my question as to why that is.

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