From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: guixsd install questions
Date: Sat, 01 Jul 2017 16:05:40 +0200
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In-Reply-To: <87d19l9p58.fsf@santanas.co.za> (Divan Santana's message of "Fri,
	30 Jun 2017 22:49:55 +0200")
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To: Divan Santana <divan@santanas.co.za>
Cc: help-guix <help-guix@gnu.org>

Divan Santana <divan@santanas.co.za> skribis:

> Ludovic Court=C3=A8s <ludo@gnu.org> writes:

[...]

>> My guess is that you=E2=80=99d need to explicitly mark one of the mapped=
 device
>> as depending on the other; this cannot be guessed.
>>
>> If you run =E2=80=9Cguix system shepherd-graph=E2=80=9D on your config y=
ou=E2=80=99ll probably
>> see that there=E2=80=99s no such dependency.
>>
>> Currently dependencies among mapped devices cannot be expressed, but
>> that=E2=80=99s easy to fix (by providing a =E2=80=98dependencies=E2=80=
=99 field as in
>> =E2=80=98file-system=E2=80=99.)
>
> So I've tried altering the code and asked on IRC a while back too. I
> tried some of the suggestions that were given but none of them worked.
>
> Would you be able to "spell out" for someone clueless what the code
> should look like to express the dependencies.
>
> Currently the code looks like this
>
>   (bootloader (grub-configuration (device "/dev/vdb")))
>   (mapped-devices (list
>                    (mapped-device
>                     (source (list "/dev/vdb1" "/dev/vdc1"))
>                     (target "/dev/md0")
>                     (type raid-device-mapping))
>                    (mapped-device
>                     (source (uuid "1c0f1601-97f4-4a3d-9528-cd76130ff919"))
>                     (target "crypt")
>                     (type luks-device-mapping))))
>   (file-systems (cons (file-system
>                        (device "/dev/mapper/crypt")
>                        (title 'device)
>                        (mount-point "/")
>                        (type "ext4"))
>                       %base-file-systems))

You can have your file system depend on the two mapped devices like
this:

   (file-systems (cons (file-system
                        (device "/dev/mapper/crypt")
                        (title 'device)
                        (mount-point "/")
                        (type "ext4")
                        (dependencies mapped-devices))
                       %base-file-systems))

What *cannot* be expressed yet is dependencies among mapped devices.
For that we need to extend the <mapped-device> record with a
=E2=80=98dependencies=E2=80=99 field like <file-system> does.

You=E2=80=99re welcome to start working on it if you feel like it (and I=E2=
=80=99d be
happy to help!) and/or submit it to bug-guix@gnu.org.

I hope this is a bit clearer now!

Ludo=E2=80=99.