Cross linker (e.g. ld from binutils-armhf) does not support any method
of setting additional link paths, and this causes problems when building
various packages. Work around this problem by calling the qemu binary
instead of the cross binary from the native chroot, whenever we are
linking.
I have tested that this allows successfully building hello-world,
coreinfo, libhybris for armhf. So this fixes#227 and fixes#228.
Regarding performance, this is the same way as distcc does it. We would
get a performance gain if we were able to use the cross-linker. But so
far I could not figure out how to patch the binutils source to make it
work like we want to have it. Maybe I'll ask on some binutils mailing
list for advice. In the meantime, this workaround should make
crossdirect work for all use-cases, and it is still faster than the
previous distcc setup, because we can avoid the overhead of setting up
and running a ssh server locally to work around missing authentication
in distcc (see pmbootstrap!1649). Let's test this for some more time,
and then make a pmbootstrap release that rolls out crossdirect for
everyone.
Instead of running compilers directly, let them go through the native
ccache binary. Note that it will still use the foreign arches cache dir
because the native cache dir would be at /native/home/pmos/.ccache.
Use execve instead of setenv and execv, because that didn't work with
LD_LIBRARY_PATH (ccache was complaining that it couldn't load zlib).
Enable -Werror, because we are maintaining this program and it helps
us catching bugs early.
A set of wrapper executables that launch native cross compilers inside
foreign chroots. Speeds up cross compilation a lot, compared to the
distcc-sshd method.
