I use 1024 MB RAM but my slackware 10.2 sees only 885 MB RAM. Any idea why?

Could be a couple of issues, you could have a bad memory stick, check to see also if your bios picks up all 1024MB of ram, I am also thinking you might need to recompile your kernel with high memory support, but that I am not sure about, because it starts from 4GB+ not 1GB....So I am thinking it could be a bad memory stick

no your problem is you need to emable highmem in your kernel

bird603568 is right. If you want to use the rest of the memory, you need to enable HIGHMEM support in your kernel. This is not gauranteed to improve performance, though, as there is an associated overhead cost with running HIGHMEM (which tends to negate the gain of additional RAM). An alternative is to use a Con Kolivas patch for your kernel. The Con Kolivas patch enables LOWMEM support for up to 1Gig of RAM.

the above posters are right. i had the same "problem" and used the ck patch. now linux recognizes all the ram.

As we are talking about the Con Kolivas patchset, I add that it has many interesting features. It allows to keep a 2.4.x Linux kernel and to benefit from desktop performance features found in 2.6.x Linux kernel such as preemptible kernel and low latency. I use it on my Duron 800 and the difference between a Linux kernel with and without it are noticeable when compiling and packaging softwares from sources : with the CK patchset, I can listen musics and browse the web while softwares are compiling, whereas without it, sound playing gets "glitches". However, it seems that the benefits are not so noticeable if you have a more recent computer than I have. YMMV ...

--
LiNuCe

BIOS and... windows see all the 1GB, so apparently memory stick is OK.

From what I can see Con Kolivas patches are only for 2.4.x Linux kernels. I use 2.6.x series.

I was thinking of HIGHMEM but in the kernel option description it is stated that when you have this option OFF you can have up to 1 GB, so it is exactly my case and for me it seemed STRANGE that I would have to enable HIGHMEM.

Anyway I've enabled HIGHMEM (4GB) but the new kernel didn't wanted to boot. Maybe I have to change something in my lilo options (I use bootsplash). I'm not at my PC so I cannot quote any system messages.

Hello!

The CK-paches are also available for the 2.6-kernels. I f you don't want all the patches you can also just pick the 1g lowmem.

Take a look at http://members.optusnet.com.au/ckolivas/kernel/

I am using the full ck-patchset myself and have been very please with both performance and stability

Now it works.
Thank you.

just a bit curious.
any idea causes this limitation?

Thanks.

Maybe this link could bring some informations :
http://kerneltrap.org/node/2450