[Nix-dev] Toward a Purer stdenv

[Shea Levy]

Thanks for this list! Lots of good targets to attack. 

Marc Weber <marco-oweber at gmx.de> wrote:

>Excerpts from Shea Levy's message of Wed Aug 17 21:37:32 +0200 2011:
>> I've been thinking about creating a nixpkgs branch to find and
>eliminate 
>> some of the remaining impurities in the Linux stdenv.
>
>"linux stdenv" ? What are you referring to exactly?
>

I don't care much about, for example, making the stdenv for OSX not depend on the system libc. 

>Impurities:
>
>- cosmic ray (they may change bits), so build results do not only
>depend
>  on your computer, but also where it is located
>

If you have an idea for how to modify stdenv to avoid this, let me know :-) 

>- amount of RAM
>
>- filesystem being used (btrfs caused different behaviour in previous
>  older kernels)
>
>- kernel (you talked about it)
>   * version
>   * settings (over commit or such)
>   * ..
>
>- hardware:
> * disk (if you think about database apps they might choose to use on
>   ore the other implementation depending on how fast your harddisk is
>   don't think this happens in practise)
>
> * CPU (features ?, eg is MMX available or not)
>
> * graphic card 
>
>* .. you can think about more issues such as USB being plugged in (does
>   not make sense, but you could write such a prog which behaves
>   differently if some kind of printer is plugged in)
>
>- time / timings
>  * clock time
>  * speed of CPU
>  * ...
>
>- number of multiple cores when using parallel builds (eg kernel
>  derivation)
>
>- running virtualized or not. Eg if you're running in a virtualized env
>  you can't run qemu tests (eg nixos installer) because you can't nest
>  vitrualized systems due to hardware restrictions (correct?)..
>
>- /dev/random (thus your keyboard input)
>  This includes builds using rand() function etc.
>  The fix is to fix builds if this happens.
> Older ghc versions may have had this issues according to a commit log.
>
>- network access
>
>- of course the user name building a package
>
>- the store location (for completeness)
>
>The impurity having had greatest impact on me is kernel version when
>trying 3.0. In fact newest kernel made btrfs worse so my fix was
>downgrade to 2.6.38.8. You don't know when the next big kernel
>numbering
>scheme is going to happen so its hard to say big the impact on us is at
>all.
>
>I'm pretty sure that I've still missed some impurities.
>
>Marc Weber
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