Determinism issue

Determinism issue

[Ondra Pelech]

Hi everybody,
I would like to bring up the issue of determinism.
I've come across this pull-request in nixpkgs

https://github.com/NixOS/nixpkgs/pull/2281

so I would like to ask, how is guix standing?
how is it good at build determinism?
this post

https://gist.github.com/madjar/545e1a9b6a8f9b7faeb8

also talks about big performace hit on GCC.
so how is it with Guix?


Best regards
Ondra

Re: Determinism issue

[Ludovic Courtès]

Hello,

Roughly, there’s not much difference between what Guix and Nixpkgs
provide in terms of build determinism, but this is clearly something
we’re interested in.

Guix may be slightly stricter in that chroot builds are the default, and
it doesn’t rely on /bin/sh being in the chroot (unlike Nixpkgs.)

You mention profile-guided optimizations.  This is *disabled* by default
in GCC, AFAIK, so GCC is definitely deterministic.

Another thing we do is build Binutils with
--enable-deterministic-archives, which makes ‘ar’ archives with zeroed
timestamps by default.

For other examples of non-determinism issues, the Debian project has a
nice summary: <https://wiki.debian.org/ReproducibleBuilds>.

Similarly, some time ago, I started looking a fixed-point builds, though
I didn’t complete that:

  https://lists.gnu.org/archive/html/guix-devel/2013-09/msg00159.html

Thanks,
Ludo’.

Re: Determinism issue

[Ondra Pelech]

oh, great, thanks for the explanation!
regarding the fixed point, from your linked mail, I don't understand
what is already accomplished and what still has to be done to reach
fixed point.
so what is the status quo?
best regards
Ondra


On Sat, Jul 19, 2014 at 3:52 PM, Ludovic Courtès <ludo@gnu.org> wrote:
> Hello,
>
> Roughly, there’s not much difference between what Guix and Nixpkgs
> provide in terms of build determinism, but this is clearly something
> we’re interested in.
>
> Guix may be slightly stricter in that chroot builds are the default, and
> it doesn’t rely on /bin/sh being in the chroot (unlike Nixpkgs.)
>
> You mention profile-guided optimizations.  This is *disabled* by default
> in GCC, AFAIK, so GCC is definitely deterministic.
>
> Another thing we do is build Binutils with
> --enable-deterministic-archives, which makes ‘ar’ archives with zeroed
> timestamps by default.
>
> For other examples of non-determinism issues, the Debian project has a
> nice summary: <https://wiki.debian.org/ReproducibleBuilds>.
>
> Similarly, some time ago, I started looking a fixed-point builds, though
> I didn’t complete that:
>
>   https://lists.gnu.org/archive/html/guix-devel/2013-09/msg00159.html
>
> Thanks,
> Ludo’.

Re: Determinism issue

[Ludovic Courtès]

Ondra Pelech <ondra.pelech@gmail.com> skribis:

> regarding the fixed point, from your linked mail, I don't understand
> what is already accomplished and what still has to be done to reach
> fixed point.
> so what is the status quo?

These was just experimentation, nothing concrete yet.

Ludo’.