Modules vs. compiled-in

tomk

DUring my continuing tweaking of kernel 2.6 on my laptop, I decided to compile certain features in to the kernel, instead of adding them as modules. My reasoning was that the related hardware is not going to change, so I am always going to need the functionality. However, the features required didn't work. Recompiled them as modules, and everything came up as expected

End result == working laptop, but why didn't it work, I wonder? Do some features HAVE to be modules? And if so, why is there the option to compile them in?

oscarBravo

What features are those? I have a custom-compiled kernel on my Gentoo desktop. Like you, I decided to compile in those features that I knew would always be used, and leave as modules the things I might or might not use. Works perfectly here, and it's much snappier than the kitchen-sink prebuilt kernel I was using on Debian.

tomk

Specifically, ALSA support and the firmware loader. When I compiled them in, ALSA just did nothing. Well, not quite nothing actually - I could launch alsamixer, and play with the sliders, and my audio apps seemed to think everything was OK, playing mp3s without a bother. No sound though. As modules, everything's fine, although to digress a little, I have to agree with typedef that the hoops you have to jump through to get ALSA going are a bit much.

The firmware loader (CONFIG_FW_LOADER) I need for my Wi-Fi card, and again, it did nothing when compiled in.

I know what you mean about Debian and the kitchen sink, alright - I installed the lastest 2.6.7 package mainly to have a look at the config file, and it really does have everything, although mostly as modules. Got rid of that soon enough. Cusotm compiles are the way to go - it takes about 50 minutes on the laptop (PIII 650MHz), so I generally time it for when I have something else to do.

My latest one should be done about now, actually - time to log in and have a look......

oscarBravo

Hm. ALSA Just Works for me. I wonder if there's anything in userspace that specifically expects to see modules, and doesn't think to check the kernel itself? Does that even make sense?

Here's the relevant chunk of my .config:

#
# Sound
#
CONFIG_SOUND=y

#
# Advanced Linux Sound Architecture
#
CONFIG_SND=y
CONFIG_SND_TIMER=y
CONFIG_SND_PCM=y
CONFIG_SND_RAWMIDI=y
CONFIG_SND_SEQUENCER=y
CONFIG_SND_OSSEMUL=y
CONFIG_SND_MIXER_OSS=y
CONFIG_SND_PCM_OSS=y
CONFIG_SND_SEQUENCER_OSS=y

#
# Generic devices
#
CONFIG_SND_MPU401_UART=y

#
# PCI devices
#
CONFIG_SND_AC97_CODEC=y
CONFIG_SND_VIA82XX=y

How are you installing the newly compiled kernel - make-kpkg, or make install && make modules_install?

tomk

Originally posted by oscarBravo
I wonder if there's anything in userspace that specifically expects to see modules

Thinking along those lines myself, I briefly suspected discover, but when I looked into it, I found that it was already handling other compiled-in stuff e.g. yenta_socket, with no problem.

Does that even make sense?

Not to me, but then I'm hardly an expert...

No point in posting my sound config - basically, it's the same as yours, except with 'm's insteadof 'y's.

How are you installing the newly compiled kernel - make-kpkg, or make install && make modules_install?

make-kpkg to compile, dpkg to install - when did you stop using Debian?!;)

oscarBravo

Originally posted by tomk
when did you stop using Debian?!;)

I haven't, really - I had done a few nasty things to my desktop system that left it crying out for a reinstall, so I decided to broaden my horizons and try Gentoo. No regrets on that front, it really is a lovely distro. I'm still running Debian on the servers; I can't think of a reason to switch.

I have an old Vaio PictureBook running Debian Sid. I'd love to put Gentoo on it also, but 64MB just isn't going to cut it for compiling an entire OS.

Back to your situation: I really can't see a problem with using ALSA as modules. If it ain't broke...?

tomk

No problem at all - I was just curious as to why it didn't work compiled-in. Working now, so I'm not going to lose sleep over it.

Time for the next thing, I think .........

nadir

some things 'like alsa' can be problematic when you compile them in, i think it can get confused over exactly what to use. Like i was having trouble with usb before, when i compiled it all in, it just wouldnt work, so i compiled uhci and ohci as modules, then i could figure out exactly what combination and settings worked best. But thats exactly the way i do it too, i compile in all the stuff im going to be using constantly and make modules out of stuff i may use, if you need to do any tweaking basically build it as a modules, that lets you mess around with it later.