Re: Loading modules built using linux-module-build-system

[Ludovic Courtès]

Hi Danny,

Danny Milosavljevic <address@hidden> skribis:

> A patch to guix master which
>
> * Puts the kernel modules (including any other packages that have 
> "lib/modules"
> inside their derivation) into /run/booted-system/profile/lib/modules
> * Ensures that depmod is invoked on that
> * Makes the modprobe wrapper use it
>
> is provided below.

Nice!

I’m wondering if we could avoid clobbering the global profile with the
kernel and module packages, though (as is currently the case.)

> --- a/gnu/system.scm
> +++ b/gnu/system.scm
> @@ -887,9 +887,11 @@ we're running in the final root."
>  (define* (operating-system-profile os)
>    "Return a derivation that builds the system profile of OS."
>    (mlet* %store-monad
> -      ((services -> (operating-system-services os))
> -       (profile (fold-services services
> -                               #:target-type profile-service-type)))
> +      ((kernel -> (operating-system-kernel os))
> +       (services -> (operating-system-services os))
> +       (profile (cons kernel (fold-services services
> +                                            #:target-type
> +                                            profile-service-type))))
>      (match profile
>        (("profile" profile)
>         (return profile)))))

The value of ‘profile’ above can never match this pattern, or am I
missing something?

> +(define (linux-module-database manifest)
> +  (mlet %store-monad
> +    ((kmod (manifest-lookup-package manifest "kmod")))
> +    (define build
> +      (with-imported-modules '((guix build utils)
> +                               (guix build union))
> +       #~(begin
> +          (use-modules (srfi srfi-26)
> +                       (guix build utils)
> +                       (guix build union)
> +                       (ice-9 match))
> +          (let ((destdir (string-append #$output "/lib/modules"))
> +                (dirs (filter file-exists?
> +                              (map (cut string-append <>
> +                                        "/lib/modules")
> +                                   '#$(manifest-inputs manifest))))
> +                (System.maps (filter file-exists?
> +                              (map (cut string-append <> "/System.map")
> +                                   '#$(manifest-inputs manifest))))
> +                (Module.symvers (filter file-exists?
> +                              (map (cut string-append <> "/Module.symvers")
> +                                   '#$(manifest-inputs manifest)))))
> +              (mkdir-p (string-append #$output "/lib"))
> +              (union-build destdir dirs #:create-all-directories? #t)
> +              (exit (zero? (system* (string-append #$kmod "/bin/depmod")
> +                    "-e" ; Report symbols that aren't supplied
> +                    "-w" ; Warn on duplicates
> +                    "-b" destdir
> +                    "-F" (match System.maps ((x) x))
> +                    "-E" (match Module.symvers ((x) x)))))))))
> +    (gexp->derivation "linux-module-database" build
> +                      #:local-build? #t
> +                      #:substitutable? #f
> +                      #:properties
> +                      `((type . profile-hook)
> +                        (hook . linux-module-database)))))

Note that this fails if ‘kmod’ is no in the profile.

Besides, I wonder how much is missing from (gnu build linux-modules) to
do this without resorting to kmod.  :-)

>  (define (xdg-desktop-database manifest)
>    "Return a derivation that builds the @file{mimeinfo.cache} database from
>  desktop files.  It's used to query what applications can handle a given
> @@ -1425,7 +1463,8 @@ MANIFEST."
>          gtk-im-modules
>          texlive-configuration
>          xdg-desktop-database
> -        xdg-mime-database))
> +        xdg-mime-database
> +        linux-module-database))

Maybe we should not add this hook by default, to avoid overhead for a
very unusual use case.  The caller of ‘profile-derivation’ could add it
when needed.

Thinking more about it, what about handling the union/profile thing in
‘operating-system-directory-base-entries’?  We could still use
‘profile-derivation’ with the hook you wrote, but we’d be able to keep
that here instead of adding it to (guix profiles).

Also, if we take that route, we would probably need a
‘linux-module-packages’ field in <operating-system>.

WDYT?

Thanks,
Ludo’.