GNU bug report logs - #55231
[PATCH v1] initrd: Allow extra search paths with ‘initrd-extra-module-paths’

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Message #236 received at 55231 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: Josselin Poiret <dev <at> jpoiret.xyz>, Tobias Geerinckx-Rice <me <at> tobias.gr>,
 Ian Eure <ian <at> retrospec.tv>, Morgan Arnold <morgan.arnold <at> proton.me>,
 Brian Cully <bjc <at> spork.org>, Leo Famulari <leo <at> famulari.name>,
 Andreas Enge <andreas <at> enge.fr>, Kaelyn <kaelyn.alexi <at> protonmail.com>,
 Felix Lechner <felix.lechner <at> lease-up.com>,
 Mathieu Othacehe <othacehe <at> gnu.org>,
 John Kehayias <john.kehayias <at> protonmail.com>,
 Christopher Baines <guix <at> cbaines.net>, 55231 <at> debbugs.gnu.org,
 Simon Tournier <zimon.toutoune <at> gmail.com>
Subject: Re: bug#55231: [PATCH v1] initrd: Allow extra search paths with
 ‘initrd-extra-module-paths’
Date: Mon, 17 Feb 2025 11:26:47 +0900

Hi Ludo,

Ludovic Courtès <ludo <at> gnu.org> writes:

[...]

>> +    (let* ((substitutable-inputs? (every substitutable-derivation?
>> +                                         (map derivation-input-derivation
>> +                                              inputs)))
>
> This change doesn’t come for free.  I didn’t follow the discussion, but
> adding overhead to such a core component to accommodate ZFS sounds
> questionable to me.

I've measured with strace -fc and time, and the difference appeared
negligible.

>> +          ;; DRV2 is *not* available as a substitute, since it has drv1 as
>> +          ;; input, and the non-substitutability is viral to avoid
>> +          ;; distributing non-substitutable items that could have become
>> +          ;; embedded, for example in an initrd.
>
> Who would distribute it though?  A build farm building a ZFS-enabled
> initrd, right?  Is that a real use case?  (Perhaps this has already been
> answered before; please let me know what I should look at, it’s a long
> discussion!)

It's that far fetch that substitute servers like berlin or third party
ones could want to use ZFS RAID 5/6 themselves to minimize disk usage
while having some redundancy, so yes, that's the most likely use case, I
think.

Then a downstream user of such build farm/substitute server could use
ZFS themselves and find themselves fetching ready-built initrd's binary
containing the ZFS module, which should not be happening due to the
license incompatibility between ZFS's CDDL and the Linux kernel GPL2
only.

-- 
Thanks,
Maxim

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