Re: "guix system reconfigure" downloads 2G of stuff it doesn't need

[Marek Paśnikowski]

"Zack Weinberg" <zack@owlfolio.org> writes:

> On Tue, Jul 30, 2024, at 10:43 AM, Leo Famulari wrote:
>> On Mon, Jul 29, 2024 at 10:31:35AM -0400, Zack Weinberg wrote:
>>> Why does it need to download all of this stuff that I know it doesn't
>>> actually need (given that "guix gc" deleted it)?  In particular it
>>> appears to be downloading build dependencies for everything whether
>>> or not it is going to use a substitute for them, and also packages
>>> that I have intentionally excluded from the system configuration.
>>
>> Very generally, these programs are considered necessary to build the
>> system generation itself.
>>
>> I'm not claiming that each of these programs is executed in the
>> process of building the generation, but they are considered by Guix
>> to be required, either directly or transitively, in order to perform
>> this work.
>
> Is there a good way to investigate _why_ each of these packages is
> considered necessary to build the system generation, and, equally
> importantly, why they are _not_ considered necessary by "guix gc"?
>

I have a hypothesis, that the process of generation preparation was
considered to be completely transient, and thus the derivations and
outputs are never registered as live items of the gnu store.