OK, back from holiday - here are some notes I made when I was away and completely isolated from the internet...
Writing this for later upload to advogato. Looking out at a rain lashed Donegal scene, after finally giving up on trying to get a serial console to appear on my Thinkpad - because I now know I cannot make it happen and why. A pity - as I know that the Dreamcast I am using is booting and mounting the nfs based file system, but I had blithely packed up the TP 600 (which I regarded as a fantastically powerful box only four years ago) workhorse, along with the cross over cable I had been given for free (as it is incorrectly marked as a patch), and the serial DC coders' cable and brought them all here without actually testing the combination.
After reading through lots of man files I now realise that I need to have the thinkpad kernel module installed to be able to correctly setup /dev/ttyS1 and so actually connect. I do have a (binary) version of the module but unfortunately it is for a 2.4.18 kernel (for some reason that is what apt/fedora downloaded) and I cannot even force load it against the 2.4.20 kernel I have. And needless to say I have no internet access and even though both my mobile phone and the TP have IR ports - I need the kernel module to set up the IR modem :(. In any case I wouldn't use the phone for downloading such huge volumes - been there, done that, paid the phone bills (or, rather, my employer did).
Still, I feel I have learned something more about how linux and the standard PC BIOS interact (having read the setserial man page) and, in the course of building the kernel found a bug/feature in ALSA. Hoping I can be the first to point this out and will not look silly! Essentially, one cannot actually build a PCM capable ALSA system unless the OSS emulation is selected. That is not a problem, except for the fact that these are separate options for kernel building. Maybe it is because one can build an ALSA MIDI system? (I haven't tried) Anyway, I think the kbuild system could be simplified and clarified on this point.
[Later same day]
Thought I'd solved my problem when I stumbled across the ``cyber cafe'' in Donegal town. But it was closed due to ``internet connection problems'', so that was the end of that. Wandering around the town I also found copies of ``Linux Format'' magazine on sale in one of the newsagents. So the revolution is spreading even to this corner of Europe, but at 11 euro a copy for what is quite thin fare I decided to let a local benefit from its contents.
Well, came close to solving all my problems with the DC and then failed at the last moment - because of inadequate preparation two weeks ago (on the last day of the holiday I could not have accomplished much anyway).
Discovered I had actually got the sources for the Thinkpad module on the TP after all, but they required the 2.4.20 kernel sources to build. Hadn't got those, but did have the 2.6.0-test2 sources (as that is what I built the DC kernel from). So, I thought, build the 2.6.0-test2 sources and (as I hadn't got the up-to-date mod tools) integrate the Thinkpad code into the kernel kbuild and build it static.
Of course, without the correct mod tools I also had to build the 2.6 kernel without modules. Started work on that at 10pm, still hadn't got a good build by 2am, so went to bed. A bit of fiddling in the morning and low-and-behold 2.6 will boot the TP (which therefore becomes first i386 machine I have managed to boot with the 2.5/2.6 series - failed many times with 2.5 kernels). Do some more tinkering to get a slightly less unwieldy kernel (another 2 hour build on this box) and then sit down to integrate the Thinkpad module into the kbuild when I notice that dmesg is actually reporting a /dev/ttyS0 and /dev/ttyS1 - so seems the Thinkpad module is redundant for that at least.
Sure enough, fire up the DC and minicom and watch DC boot. Very exciting, but also time to take kids out the the beach (this is a family holiday!).
When I get back and kids are safely off to bed, and we're all packed for morning's journey, have another go, but realise I don't have the SH mod tools either. Even when I unpack the old ramdisk initrd and mount that on loop, they aren't there either! A stupid mistake and if I'd thought about this for a few minutes when I was setting up this box to go in London, I'd have realised.
So code is there, module is built, but I won't be able to load it till I am back in London again.
On the beach finished ``Cathedral and the Bazaar'', have to say I found it all rather less than illuminating and too keen to push its (rightist libertarian) political slant while attacking everybody else for bringing politics to the table. Also looks very over blown in the light of the continuing IT slump.