Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 1 Mar 2013 14:03:34 -0600

Hi Ben,

On 2013-03-01 Benjamin Franksen wrote:
> Am Freitag, 1. März 2013, 17:50:41 schrieben Sie:
> > The main
> > reason is that we have a dependency in place so that no cross-builds can
> > start until after the host build has completed.  Those files will usually
> > be built and installed as part of the host build, so make will see them
> > as already up to date when it later checks them for each of the
> > cross-build targets.
> 
> Thanks, I was not aware of this. Since when is this the case (i.e. only in
> 3.15 or is it in 3.14.12, too)?

This was added in 3.14.11 (see the Release Notes).

> And: will this same dependency (CROSS builds depend on HOST build to be
> complete) not also ensure that all architecture independent targets are
> already up-to-date when the CROSS build starts, so generating them directly
> inside $(COMMON_DIR) is not done multiple times in parallel? (Assuming, of
> course, that the rules are written to avoid accidental parallelism due to
> multiple targets in a non-pattern rule, as I explained in a previous
> message).

That's how we designed it work.  However some people put conditionals into 
their Makefiles which might disable the DBD file generation on the host for 
example.  Private rules that don't have correct dependency settings can also 
result in the actions being run on all targets, and if the user never tries 
parallel builds they might not notice this.

Problems with parallel builds can show up sooner or more often on Windows 
because there the file-system won't let one process delete a file that another 
process has open.

- Andrew
-- 
There is no such thing as a free lunch.  When invited for lunch,
it is best to check if you are there to eat, or to be eaten.
-- Clive Robinson

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System