Re: Issues and improvement for `kernel-loadable-modules'

[Brice Waegeneire]

Hello Danny,

Sorry for the empty email; cancel and send buttons were too close for
me...

On 2020-03-26 15:13, Danny Milosavljevic wrote:
> Hi Brice,
>
> On Thu, 26 Mar 2020 14:34:03 +0000
> Brice Waegeneire <address@hidden> wrote:
>
> > First I was expecting the packages in `kernel-loadable-modules' to use
> > the
> > `kernel' field as their kernel input or to have a simple procedure to 
> > do
> > so. Otherwise you get a “Specified Linux kernel and Linux kernel 
> > modules
> > are not all of the same version”. It makes it more difficult that it
> > needs
> > to be to write composable configurations; IOW why would I want to use 
> > a
> > module built with a different kernel that the one I'm specifying in my
> > `operating-system'.
>
> Because packages are modular, changing the build system can only be 
> done
> retroactively by a procedure.  We could totally do that but it would 
> make
> the kernel-loadable-modules field more magical and more difficult to 
> debug.
> Also, I guess it would hard-code linux-module-build-system for those
> (right now you can use whatever build system you want).  Do we want it 
> anyway?

Magic isn't the way to go, for sure. I tried writting a procedure to 
abstract
it, but I wasn't successful: see my second issue with inferiors, the 
fact that
it only handle `linux-build-system' and that I need to use a direct 
reference to
a package. On that last point I would like to use something like
“(operating-system-kernel this-operating-system)” to reference the 
kernel
but my guile foo isn't good enough: “this-operating-system” has to be in 
scope
 of “operating-system”. Following is the procedure I'm talking about:

--8<---------------cut here---------------start------------->8---
  (kernel-loadable-modules
   (map (lambda (module)
          (package/inherit module
                           (arguments
                            (ensure-keyword-arguments
                             (package-arguments module)
                             `(#:linux ,my-linux)
                             ))))
--8<---------------cut here---------------end--------------->8---


> > And last issue, we are missing a service to load module manually when
> > they
> > can't be auto-loaded as it's the case with `ddcci`[1]. I have managed 
> > to
> > solve this one by writing my first service
> > `load-kernel-modules-service'.
> > What can I improve before submitting it as a patch -- except the 
> > missing
> > documentation?
>
> I think that things should be described by nouns and actions should be
> described by verbs.
>
> So "load-kernel-modules-service" sounds really wrong to me.
> Maybe "kernel-module-loader-service"?
>
> Others don't care so much because Scheme kinda erodes the boundary 
> anyway.

That's definitely a better name.

> Otherwise looks good to me.
>
> I guess it could be nice to be able to extend this service from other 
> services
> using (service-extension load-kernel-modules-service-type '("module1"
> "module2")) or something.

I think it's already the case, there are `compose' and `extend' fields 
in the
`service-type' and I tried it with
“(simple-service 'ddcci-module kernel-module-loader-service-type 
'("ddcci"))”.

Brice.