Re: Determination of default configuration values for build projects and checking the settings

[Eric Blake]

On 07/11/2017 05:43 AM, SF Markus Elfring wrote:
> Hello,
> 
> I find the following information interesting once more.
> https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Site-Defaults.html
> “…
> Autoconf-generated configure scripts allow your site to provide default values
> for some configuration values. You do this by creating site- and system-wide
> initialization files.
> …”
> 
> 1. Will it become possible to select such defaults only for specific software
>    build projects?

Unless someone writes a patch to autoconf (and then you propagate the
use of that new autoconf to all affected packages), it is only possible
to select per-package defaults insofar as those packages stick to
per-package cache variable names.

> 
> 2. These values will be passed to configuration and make scripts.
>    How much do you trust that they are really usable?

If you don't trust site-wide defaults, then don't install them.

>    If you would like to perform validation checks again, I am looking for ways
>    to avoid corresponding code repetition there.

Site-wide defaults set cache variables in order to avoid repetitive
testing; but if you don't trust the installed site-wide defaults that
you get when you avoid the testing, then what DO you trust?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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