After installing Slack 11 with the 2.6 kernel huge26.s I was unable to build up a pppoe connection. In fact, the needed configuration files not only refused to install in /var/run but they were even vanishing (if put manually) whenever trying to # pppoe-start. Then I did reinstall Slack 11, but with a 2.4 kernel instead, and now my pppoe connection is OK. However, since interested in 2.6 kernels (for some other reasons) I would appreciate opinions about (in)compatibilities with pppoe setups.
Thanks!

Don't know anything about pppoe - I simply don't use it. But, since you are asking about 2.6 kernel in Slackware 11, a very popular mistake with 2.6 kernels is not having the kernel modules from extra or testing dirs installed... did you install the modules (they don't install automatically)?

Thanks for pointing me out, I didn't even try anything in that matter. So, maybe I should have a look on the configuration file of the kernel to see which modules are needed and which items are built in the kernels. Is there a quicker method than this one?
Thanks again!

It's recent thread here about installing the modules, but the simplest possible way to install modules is to cd into extra/linux-2.6.17.13 directory on slackware DVD/CD and install the modules package:
installpkg kernel-modules-2.6.17.13-i486-1.tgz

(This applies for huge26.s kernel, for test26.s kernel you must go into testing dir)

As a sideplot I'd like to mention a thing I've noticed with my own pppoe connection; I'm not sure if it's up to the way my ISP has laid the connection and the ethernet aside it, but often I encounter a situation where a pppoe connection is established, but dhcp fails to work even though it's set up correctly (by this I mean the settings that do work on the same machine with other systems and on the same system with some tricks); the reason behind this seems to be related to the ethernet the same eth card connects to. In my case the device eth0 gets an ethernet ip address, and in addition the ppp0 created by pppoe connection gets the "real" internet ip. Not sure what exactly goes wrong, but automatical connection can't be established, I'll always have to disable the adsl connection, put eth0 down (ifconfig eth0 down), then re-establish the pppoe connection to get dhcp information correctly.

I've tried to alter all relative configurations in numerous ways but the problem seems to persist; this happens on both 2.4 and 2.6 kernels, so this leads me to think it's got something to do with the ethernet environment provided by my ISP (it's not a regular connection, but goes through a subnet).

I did have a look on the .config file of huge26.s and it turned out that definitely I do need to load some modules. However, my inspection cann't compare to the efficient method described by Kleb (it's realy great, thanks!). As for bOuncer's remarks, I do confirm that the authomatic launch of pppoe always failed on my system (irrespective of using 2.4 or 2.6 kernels).
Thanks a lot!