Out of kernel module question

Jeremy31 · February 18, 2025, 10:33pm

Since the 6.8 Ubuntu kernel uses zstd compressed modules, does anyone know what triggers the compression in out of tree modules? I have multiple projects on github that use dkms that work fine but some other projects don’t trigger the compression

1fallen · February 18, 2025, 11:05pm

Is there anything useful in “man zstd”

Jeremy31 · February 18, 2025, 11:13pm

Not that I saw, but man pages are usually out of date. I was able to get the modules to load after using zstd on them. My search skills must not be good or I am using the wrong key words

wxl · February 18, 2025, 11:40pm

Would this be better in Kernel ?

Jeremy31 · February 18, 2025, 11:47pm

Might be, I thought about posting it there

ogra · February 19, 2025, 12:13pm

You’d rather want to look at dkms and its documentation, not at the manpage for zstd. IIRC dkms just looks for the compression used in the kernel config (there should also be a way to override this in case you need/want to though):

github.com

dell/dkms/blob/8a8a9d1a38fae432ec8734cc1977bdd97666f773/README.md?plain=1#L97


      
          use `dkms install` to install any of the pre-built modules.
          
          Of course, since module source will not be located in your dkms tree, you will
          not be able to build any modules with DKMS for this package.
          
          Module signing
          --
          
          By default, DKMS generates a self signed certificate for signing modules at
          build time and signs every module that it builds before it gets compressed in
          the configured kernel compression mechanism of choice.
          
          This requires the `openssl` command to be present on the system.
          
          Private key and certificate are auto generated the first time DKMS is run and
          placed in `/var/lib/dkms`. These certificate files can be pre-populated with
          your own certificates of choice.
          
          The location as well can be changed by setting the appropriate variables in
          `/etc/dkms/framework.conf`. For example, to allow usage of the system default
          Ubuntu `update-secureboot-policy` set the configuration file as follows:

Jeremy31 · February 19, 2025, 9:44pm

Thanks, now just to dig through dkms code

system · February 22, 2025, 9:44pm

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