building the same project for two boards in parallel is not possible

[LudwigKnuepfer]

As I understood it, this should be possible by now..

[OlegHahm]

Could you, please, be a little bit more verbose? What exactly do you mean by "in parallel" and "not possible". Calling make BOARD=native and make BOARD=msba2 works fine for the default project.

[LudwigKnuepfer]

For examples/default run: make BOARD=native -B clean all & make BOARD=msba2 -B clean all

mv: cannot stat ‘/tmp/riot_out’: No such file or directory
/foo/RIOT/examples/default/../../Makefile.base:34: recipe for target '/foo/native/RIOT/examples/default/bin/msba2/posix_io.o' failed

[OlegHahm]

Could not reproduce. Works without problems here. However, I would not guarantee that two RIOT build processes at the same time are safe. I would not see this as a bug, but rather as an enhancement, if that.

[LudwigKnuepfer]

Well, try again .. maybe your computer is too fast ;-)

Obviously, if two build processes use /tmp/riot_out as an intermediate file this is error prone.

[OlegHahm]

Agreed. Do we need this feature?

Secondary question: Do we need these .d files anyway?

[LudwigKnuepfer]

I don't know if we need support for parallel building, but this use of a /tmp file should be fixed in any case.

[Kijewski]

@OlegHahm the .d files are needed. Otherwise changes to .h files won't get the .o file recompiled. Without the .d files the .o file only depends on the corresponding .c file.
Please see #584.

[kaspar030]

I agree with ludwig that usage of /tmp is a bug...
Parallel building (of boards and projects) speeds up any multi-platform CI... Would be very nice to have for all of us that have workstations that are fast enough to build everything at once.

[mehlis]

as first fix we can use http://linux.die.net/man/1/mktemp to have a safe folder to work with

[OlegHahm]

Fixed by #710

[LudwigKnuepfer]

It was also fixed by #778