Best of Technical Support

Since becomming a subscriber in 1998, I have been using the tips in the Best of Technical Support column. Sometimes I laugh at basic problems, thinking “this will never happen to me”--until now.

I am using Red Hat 5.0. A bad shell script accidentally removed my /dev! I shut down my Linux system and rebooted before restoring /dev from backup. So, I cannot restore the /dev from tape using my rescue diskette, because /dev/st0 is gone. What are the steps to recreate a basic /dev directory using my rescue diskette? After that, how do I restore the /dev with tar?

—Rene, rene.diependaele@ibbbs.be

Your rescue media also should have the default minimal set of devices, and you could copy them to your now-empty /dev directory with cp -av /dev/* /mnt/dev/ (if your disk is mounted under /mnt). Then you can boot your system with linux init=/bin/bash at the LILO prompt, and you will need very few devices.

—Marc Merlin, marc_bts@valinux.com

Then, to restore st0, do a mknod /mnt/dev/st0 c 9 0.

—Christopher Wingert, cwingert@qualcomm.com

I have a Soyo K7V Dragon with a 1,400MHz Athlon with BIOS settings for “optimized defaults”. I installed 1.5GB Nanya PC2100 memory and Red Hat 7.2. The system boots and runs but crashes sporadically. No messages in syslog, just “restart....” When I remove 512MB of the 1.5GB, the system runs fine.

I've tried dozens of combinations of distributions, kernels and BIOS settings, as well as several disk configurations (hardware RAID, software RAID, no RAID, disk on Promise controller only, disks on Via controller only) to no avail. The distribution kernels do not recognize the via8233 southbridge. I made appropriate modification to via82cxxx.c and recompiled the kernels. The southbridge is found, but the system still crashes.

I finally replaced the memory, but the problem persists. The 512MB DDR sits burning a hole in my desk. It was expensive ($199/stick). Of course, it's cheaper now, but I'd still like to get this system running to its potential.

—Jim Peterman, jptr@msn.com

Did you replace all the sticks or just one? If only one, you might want to replace them all.

—Christopher Wingert, cwingert@qualcomm.com

It is possible that you have a defective memory slot on your motherboard, or that it's not reliably able to power more than two slots of RAM.

—Marc Merlin, marc_bts@valinux.com

I've been receiving Linux Journal for a couple of years now and follow most of the technical things in there. But now I have a technical question I can't solve concerning the Teles PCMCIA/S0 card and kernel 2.4. I searched the Internet, newsgroups, etc., for solutions but found none. What I did find in the newsgroups are other people that have the same problem. Maybe you can help us out here.

When I used kernel 2.2.x I always used the Teles PCMCIA/S0 card. No problem at all. When compiling a new kernel, I also needed the extra PCMCIA card services and a patch downloaded from home.wtal.de/petig/ISDN, and everything worked fine. However, from kernel 2.4 this patch cannot be used anymore—it just won't compile. In the documentation of the kernel sources for 2.4, it says that they support the Teles PCMCIA/S0 card. But, whatever I try I can't get it to work. It always complains about not having the right I/O address, even when I use the IRQ and I/O that I used with the 2.2.x kernel release. The second thing is when inserting the card, I always get the message that the kernel looks for module teles_cs.o. This was the one from the home.wtal.de/petig/ISDN site.

Is there any way you can help me and all the people that want to use this ISDN card? I'm now using the standard Red Hat 7.1 version with all the patches applied.

—Andre Seesink, a.seesink@chello.nl

You might want to verify that the IRQ and I/O address you specify are still valid. Sometimes when you boot other OSes, I/O ports/IRQs on some Plug-and-Play devices are moved automagically.

—Christopher Wingert, cwingert@qualcomm.com

I haven't had much luck with the kernel PCMCIA support myself. David Hinds (the pcmcia-cs author) recommended that I try disabling PCMCIA in the kernel (you'll have to recompile your kernel with PCMCIA disabled), and that I try using the standalone pcmcia-cs package. My problems have gone away since I've done that. Yours may too.

—Marc Merlin, marc_bts@valinux.com