Re: Compiling for newer Intel CPUs with an older Intel build system?

[Nick Bowler]

On 2016-03-04, Sean Byland <address@hidden> wrote:
> On 3/4/16, 12:24 PM, "Nick Bowler" <address@hidden> wrote:
>>On 2016-03-04, Sean Byland <address@hidden> wrote:
[...]
>>> 2. Generating a config.cache on the Ivybridge compute node, which
>>> shares the majority of the file system with the Sandybridge system
>>> and can successfully execute everything. Then point configure on the
>>> sandybridge system at the cache generated while using the Ivybridge
>>> CPU.
>>
>> This will work fine if the systems are similar enough, although
>> probably simpler to just directly share the build directories rather
>> than mucking with config.cache.
>
> I agree that this is good option. The only reason I liked the cache
> idea is because I thought it would be neat to be able to generate a
> substantial cache that could be used for multiple autotools projects,
> so compiles could be performed with users don’t have access to the
> newer runtime system.

This sounds like a nice idea in concept, but unfortunately the
config.cache files are not meant to be shared between different
packages.  This has been tried before, and it inevitably leads
to disaster.  Most obvious is the possibility of namespace
collision (two packages could use the same variable name for
totally different things) but more subtle issues can come up
too.

Setting specific cache variables to handle specific cases is
another story (and often necessary for cross builds).

Cheers,
  Nick