Hello,
I'm reviewing how GNU GuixSD/Linux boot,

$ cat /proc/cmdline
BOOT_IMAGE=/gnu/store/jnww66749r8ck6l2rwgvpzzbnazs0392-linux-libre-4.15.5/bzImage --root=root --system=/gnu/store/qcia33hqzi6md3q18frs16piis6xxy9i-system --load=/gnu/store/qcia33hqzi6md3q18frs16piis6xxy9i-system/boot

To perform the activation is done as a parameter through the scheme file '/var/guix/profiles/system/boot'.

In GNU Hurd as a workaround I add the lines to the '/libexec/rc' file:
--
echo running GuixSD boot ..
guile -s /var/guix/profiles/system/boot
--

After loading GNU Mach and GNU Hurd it shows:
--
In unknown file:
             ?: 9 [apply-smob/1 #<catch-closure 1a3920>]
          In ice-9/boot-9.scm:
            66: 8 [call-with-prompt prompt0 ...]
          In ice-9/eval.scm:
           432: 7 [eval # #]
          In ice-9/boot-9.scm:
          2412: 6 [save-module-excursion #<procedure 1b4ce0 at ice-9/boot-9.scm:4084:3 ()>
          ]
          4089: 5 [#<procedure 1b4ce0 at ice-9/boot-9.scm:4084:3 ()>]
          In /var/guix/profiles/system/boot:
             1: 4 [#<procedure 223900 ()>]
          In unknown file:
             ?: 3 [primitive-load "/gnu/store/rjp22rca3gv8lrrbb9j4sry9i3n1bvlp-activate"]
          In ice-9/eval.scm:
           432: 2 [eval # ()]
          In /gnu/store/6dvydkcda77dxkpbn5jsj4vsmr19gb7v-module-import/gnu/build/activatio
          n.scm:
           449: 1 [activate-current-system #f]
          In unknown file:
             ?: 0 [symlink #f "/run/current-system.new"]

          ERROR: In procedure symlink:
          ERROR: Wrong type (expecting string): #f
--

I have the following questions:

a) In GNU Hurd, how should activation be done?
b) Regarding the error assuming that I start reading from the bottom up 'ERROR: In procedure symlink',
    in GNU Hurd I guess I should try 'symlink' through guile to see if the procedure exists.

Some thoughts?

Thank you
Rene