Relevant Specs:

Thinkpad R40
1 GB ram
Dual boot Slackware Linux 10.0 and OpenBSD 3.5

I recently upgraded my memory to 1 GB ( 512 + 512 ). When I booted into Linux, PCMCIA did not work (It worked fine before I upped the ram). Assumed that it was faulty ram. Going back to the 512+256 config I had before worked just fine. Also switching the old 512 chip for the new 512 chip worked just fine. Everything worked except for both 512 chips at the same time.

Booted OpenBSD, PCMCIA works just fine, with the full 1 GB ram.

Thinking that it's a configuration issue in Linux, but I have no idea what, is there a kernel setting or something that I need to mess with here?

I believe that you need to enable highmem in your kernel. Try: That probably says that you only have 896 megs of ram. Just a guess.

I thought you only needed to use highmem support if you have 4gigs or more. .. .

This is an odd problem.

Well, searching the forum for highmem seems to show different. The highmem is for 1-4gig, according to what I've read here. Did free-m show all of your ram?

Well that's good to know. . . I am about to upgrade my main computer's ram to a gig and a half, now I know that I need to rebuild my kernel (sigh, again). . .

No luck with or without highmem, checked memtest86 anyway and it came out with no problems.