bug#20067: fix interpretation of grub configuration

[Ludovic Courtès]

Good news!

address@hidden (Ludovic Courtès) skribis:

> Tomáš Čech <address@hidden> skribis:
>
>> Grub configuration interpretes `linux' as directory where is located
>> bzImage. If I enter file name instead, result configuration will be
>> wrong.
>
> The solution will be to not automatically append “/bzImage” (and
> likewise for the initrd.)
>
> We could change places where ‘menu-entry’ is instantiated to:
>
>   #~(string-append #$kernel "/bzImage")
>
> However, there’s the problem that the image name appears in the
> ‘parameters’ file of the system (as seen in the output of ‘guix system
> build foo.scm’), where it is unevaluated.  If we use ‘string-append’ as
> above, a raw (string-append …) sexp will appear in there, which is not
> nice.
>
> To address this, an idea is to add “expanders” for gexps: gexps already
> have “compilers”, and expanders would be similar except that they would
> produce something possibly different from just the derivation’s output
> file name.  For instance, we could write:
>
>   (file-append kernel "/bzImage")
>
> and that would expand directly to:
>
>   "/gnu/store/…/bzImage"

AFAICS this is finally fixed!

  expanders in commit ebdfd776f4504c456d383ee8afa59fc6fdfc6756
  ‘file-append’ in commit a9e5e92f940381e3a4ee828c6d8ff22a73067e17
  kernel file name in commit 44d5f54e31039d78f156bd9562dca293124eaa76

Please let me know how it goes!  In particular, does it work for the
dual-boot scenario you were interested in?

Thanks,
Ludo’.