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Kernel PCMCIA problem

June 29, 2008 — BarryK
I have just confirmed it, the kernel is the cause of my PCMCIA modem not working.

This is the same modem that I got working with the kernel, as reported in this blog.

I wondered if I had made some inadvertent change in the boot scripts that somehow has adversely affected the modem, so I did an experiment, built two identical live-CDs, differing only in choice of kernel (and modules of course), booted each with 'pfix=ram', then for each I hotplugged the PCMCIA modem.

With the kernel I get this in 'dmesg':
0.0: ttyS0 at I/O 0x3f8 (irq = 3) is a 16550A
and 'wvdialconf' recognises a modem at /dev/ttyS0. With the I do not get that line in 'dmesg' and there is no modem at ttyS0.

So, the first thing I need to do is rethink all the patches that I put in the source. These are the same patches as in the kernel:

loglevel changed from 7 to 3, squashfs 3.3 (patch from Ubuntu as official patch fails), unionfs 2.3.3.

For the there are in addition:

Dazuko 2.3.5 security, CIS long filenames, 'perm' patch for Aufs.

The 'perm' patch is required as a consequence of the Dazuko patch, and just exports a symbol, so is probably harmless. That leaves the Dazuko and CIS patches.

What troubles me about the CIS patch is there may be a reason why the filename length has been set at 14 characters. It may have something to do with PCMCIA. If a kernel developer comes along without knowing the history and "fixes" it, perhaps that is the cause -- but I'm just speculating, it could be something else entirely different in the kernel that is causing this problem.


Username: BarryK
I am disappointed that the Unionfs developers have not responded to my bug report, as I want to put an updated unionfs patch into the new kernel. I made a report to their bugzilla on the 20th of this month, and to their mail-list a few days before that. Since then, someone else has posted to the mail-list about a kernel oops when using unionfs with Firefox 3, no reponse to them either. I presume that being academics and students, they are on holiday or having an inter-semester break. So, I will probably build a kernel for pup 4.1alpha3 but treat it as temporary. The thing is, I want to build a kernel that we can stay with for a considerable time, so 4.1alpha4 will have that "final" kernel.

Tags: puppy