Control: clone -1 -2
Control: notfixed -2 6.6+r27746-3
Control: severity -2 important
Control: retitle -2 nwchem builds on amd64 with -mtune=native
On Fri, Nov 18, 2016 at 12:24:04PM +0000, Debian Bug Tracking System wrote:
>...
> * debian/patches/19_disable_march_native.patch: New patch, disables
> -march=native on amd64, by Edoardo Apra (Closes: #840186).
>...
> Date: Sun, 09 Oct 2016 14:59:15 +0300
> From: Adrian Bunk <b...@stusta.de>
> To: Debian Bug Tracking System <sub...@bugs.debian.org>
> Subject: nwchem builds on amd64 with -march=native
>
> Source: nwchem
> Version: 6.6+r27746-2
> Severity: grave
>
> src/config/makefile{,-legacy}.h sets -march=native
> and -mtune=native in amd64 builds.
>
> -march=native means the code will only run on machines with a CPU
> compatible with the one on the machine where the package
> was built.
>
> Building on a different buildd machine can also change
> where the code can run - including breaking existing
> setups in stable updates.
>
> -mtune=native is less fatal, but in addition to (rare) problems
> due to the fact that the program is compiled differently depending
> on the build machine it makes the build non-reproducible.
>
> Please remove -march=native and -mtune=native
-march=native was removed, but -mtune=native is still present.
This is less bad, but still a bug:
The resulting code is now expected to run everywhere, but it will be
different depending on what build machine was used.
This leaves an opportunity for strange bugs that disappear when
recompiling (on a different machine).
And it makes the build non-reproducible.
Please also remove -mtune=native.
Thanks
Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
