Hi Paul,
On Mon Jun 10, 2019 at 16:50:57 +0200, Paul Boddie wrote:
In attempting to investigate building L4Re/Fiasco.OC for the Raspberry Pi Zero, I encountered an unusual problem: unusual because, I suppose, most people do not try and cross-build on architectures other than x86(-64).
When performing the initial L4Re build directory initialisation step...
make B=mybuild
...BUILD_ARCH seems to be set to x86 even on other architectures. This then causes CCXX_FLAGS to be populated with x86-dependent settings such as -m32, and the gcc host compilers for MIPS raise errors upon encountering these unrecognised arguments.
Here is the offending command in the top-level Makefile (line 376 in my version, r83 in Subversion):
GENDEP_OUTPUT=$$X.out $(CC) $(CCXX_FLAGS) -c $$X -o $$X.o
Although it seemed like the config step could be performed after ignoring these errors, I did wonder if there might be some undesirable consequences. In the end, I found that the following invocation was needed:
make B=mybuild CC=gcc CXX=g++ LD=ld BUILD_ARCH=mips CPU=32r2 CPU_ABI=32
After that, things seem to work as expected. I imagine that there is a "chicken and egg" situation here: the appropriate settings would be obtained from the configuration, but the command being run sets up the configuration.
Has anyone else seen this problem before?
That's a good point. You can do "make B=builddir T=arm-rv" to immediately switch to the target architecture. I'm trying to improve the handling here as I just stumpled into this in a different setting as well.
HTH, Adam