First time using custom kernel, iwlwifi modules not loading

CarterCox · n00b Joined: 28 Jan 2018 Posts: 34

Hi again! So this is the first time I manually configured the kernel instead of using genkernel all. The thing is, I'm getting some errors that don't allow my wireless adapter to show up. So here is my dmesg:

https://pastebin.com/hJiucSzw

Maybe the relevant parts:

peje · Tux's lil' helper Joined: 11 Jan 2003 Posts: 100

Hi CarterCox, you need the firmware for your wifi card, it should be in /lib/firmware.
Some of the firmware files are avaible in portage.
sys-firmware/iwl6050-ucode
cu Peje

CarterCox · n00b Joined: 28 Jan 2018 Posts: 34

Hi peje, thanks for the answer. Two questions:

How do I use this firmware
Why does using "genkernel all" solve it? What should I change in my kernel configuration to achieve this?

khayyam · Posted: Sat Apr 21, 2018 11:36 am Post subject:

NeddySeagoon · Posted: Sat Apr 21, 2018 2:53 pm Post subject:

CarterCox,

To generalise what khayyam said, any kernel module that loads firmware does it when the module is initialised.
Therefore the firmware must be available at that time.

When the kernel module is configured as <M>, root will be mounted before the module is initialised, therefore the firmware can be read from the root filesystem.
Usually /lib/fimware.

With the kernel module configured as <*>, the code is loaded by the boot loader and initialised before root is mounted so /lib/fimware cannot be read.
You must include all required firmware in the kernel binary. When you do this, /lib/fimware is read at kernel build time.

Check your dmesg. Your error

Hu · Moderator Joined: 06 Mar 2007 Posts: 21635

The driver will automatically seek and use the firmware when the driver initializes. If the driver is builtin, it initializes very early, before your root filesystem is available. If the driver is a module stored on the root filesystem, it necessarily cannot be loaded nor initialized until the root filesystem is available. In the former case, installing sys-kernel/linux-firmware is necessary to enable you to fix the problem, but is insufficient because the firmware is installed on the filesystem, and is therefore not yet available when a builtin driver initializes. As khayyam suggests, a common solution (and the easiest solution, though not the only solution) is to use CONFIG_EXTRA_FIRMWARE to embed at compile time a copy of the required firmware in the kernel. Such embedded firmware is then available before the root filesystem mounts, so the driver can find and use that firmware even before root is available. As an alternative, you could go back to building iwlwifi as a module. According to khayyam, whom I have no reason to doubt, though I've not checked this personally, genkernel made iwlwifi a module. You could choose to make it a module in your hand-configured kernel, independent of using genkernel.

NeddySeagoon · Posted: Sat Apr 21, 2018 3:03 pm Post subject:

Hu,

Genkernel makes a fully modular kernel. You get every module known to Linus :)
Well, the ISA modules are not built ... but they could be.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

CarterCox · n00b Joined: 28 Jan 2018 Posts: 34

Ok guys. Thanks for all the good information. It has beemn very helpful. However, I think the problem was something else. I had followed the wiki article: https://wiki.gentoo.org/wiki/Iwlwifi#When_using_built-in_configuration and always forgot to run "make install" after re-building the kernel, so all my changes were useless. Very dumb, I know.

Nevertheless it was an enlightening thread. Thanks again!

By the way, an off-topic question. The remnants of the old kernel are still in my /boot partition. Should I jsut manually erase them if I don't need them anymore? Should I do something else to completely get rid of it?

NeddySeagoon · Posted: Sat Apr 21, 2018 6:59 pm Post subject:

CarterCox,

Kernel bits and pieces get installed to /boot and to /lib/modules

I tend to keep 3 or 4 kernels in /boot and listed in the grub menu but rarely clean out /lib/modules.
I only have about 12 modules though.

I'm not aware of a tool to clean out old kernels but there may well be one.

Old kernels includes their matching initrd.
Off topic but related. If you don't put kernel modules in your initrd, it becomes kernel agnostic, so no need to rebuild it every kernel update.

-- edit --

khayyam · Posted: Sat Apr 21, 2018 7:44 pm Post subject:

CarterCox · n00b Joined: 28 Jan 2018 Posts: 34

Interesting! This was a good learning experience. Thanks a lot!