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From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: =?utf-8?Q?=E2=80=98guix?= system =?utf-8?Q?vm=E2=80=99?= and shared
	store
Date: Sun, 28 Aug 2016 16:22:21 +0200
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	(David Craven's message of "Sun, 21 Aug 2016 19:38:13 +0200")
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To: David Craven <david@craven.ch>
Cc: guix-devel <guix-devel@gnu.org>

Hi,

David Craven <david@craven.ch> skribis:

> So guix doesn't work inside a vm - because /gnu/store is mounted
> readonly.

Right, and also because =E2=80=98guix system vm=E2=80=99 creates a VM that =
shares its
store with the host system.

> To be able to offload arm builds once guix system vm
> --system=3Darmhf-linux works, /gnu/store needs to be writeable.
>
> Can multiple daemons concurrently use the same store?

No.

> or alternatively, can we move the
>
> (unless (zero? (system* unionfs "-o"
>
> "cow,allow_other,use_ino,suid,dev,max_files=3D65536"
>                                 "/rw-root=3DRW:/real-root=3DRO"
>                                 "/root"))
>           (error "unionfs failed"))
>
> to after the 9p filesystems have been mounted, so that the unionfs
> allows writing to /gnu/store too?

Yes, something like that: we need to make /gnu/store a union of the
host=E2=80=99s /gnu/store and a writable tmpfs, and we need to make sure
/var/guix/db/db.sqlite is populated appropriately (images produced by
=E2=80=98guix system vm-image=E2=80=99 do the latter.)

HTH!

Ludo=E2=80=99.