Problems encountered: expanded memory

The main problem I ran into was a simple one to fix, but took quite a while to track down.

The memory module, expanding my system from 4 MB (on the motherboard) to 8 MB was causing trouble. I had been worried that the on-board interface to the memory was faulty, or poorly designed, but after installing the new module (an official Toshiba upgrade of 4 MB), there seems to be no trouble. Extensive testing into the effectiveness of the upgrade has not yet been completed.

I noticed that the howto relating to the T-4500 also mentioned a problem like this, although the problem in that case was fixed when booting from the harddrive.

The actual problems I ran into seemed to center around the swap partition. This (naturally enough) led me astray, into thinking that my harddrive was malfunctioning. However, many consecutive tests proved that to be wrong.

I would typically get kernel panics, and unexplainable errors, such as the display freezing, etc. One of the most common errors was

swap_free: swap map entry bad (in 00008000)

or something like that. Typically, I would get between 3 and 15 of those errors upon shutdown, after doing just about anything. If I tried anything really big, like compiling the kernel, I would get segmentation violations and other fun things (specifically, GCC would return errors 4 and 11, which should never happen). Trying to run PGP on a large document (say, the XFree HOWTO) would also produce errors. It seemed to be that any program large enough to have to do I/O to the additional memory would cause problems.

If you're experiencing these errors, and have an add-on memory module: try taking it out. I realize it's painful to run in 4 MB, but give it a try and see if the errors clear up. If they do, you may have defective memory like I did.

This page was designed and implemented by Ian Johnston. Check out my homepage for a laugh...