On Tue, Jul 16, 2019 at 10:15:47PM +1000, Michael Ellerman wrote:

Segher Boessenkool [off-list ref] writes:
And it's definitely calling ar with no flags, eg:

  rm -f init/built-in.a; powerpc-linux-ar rcSTPD init/built-in.a init/main.o init/version.o init/do_mounts.o init/do_mounts_rd.o init/do_mounts_initrd.o init/do_mounts_md.o init/initramfs.o init/init_task.o

This uses thin archives.  Those will work fine.

The failing case was empty files IIRC, stuff created from no inputs.

So presumably at some point ar learnt to cope with objects that don't
match its default? (how do I ask it what its default is?)

The first supported target in the --help list is the default, I think?

$ powerpc-linux-ar --help
 [...]
powerpc-linux-ar: supported targets: elf32-powerpc aixcoff-rs6000 elf32-powerpcle ppcboot elf64-powerpc elf64-powerpcle elf64-little elf64-big elf32-little elf32-big plugin srec symbolsrec verilog tekhex binary ihex

$ powerpc64-linux-ar --help
 [...]
powerpc64-linux-ar: supported targets: elf64-powerpc elf64-powerpcle elf32-powerpc elf32-powerpcle aixcoff-rs6000 aixcoff64-rs6000 aix5coff64-rs6000 elf64-little elf64-big elf32-little elf32-big plugin srec symbolsrec verilog tekhex binary ihex

$ powerpc64le-linux-ar --help
 [...]
powerpc64le-linux-ar: supported targets: elf64-powerpcle elf64-powerpc elf32-powerpcle elf32-powerpc aixcoff-rs6000 aixcoff64-rs6000 aix5coff64-rs6000 elf64-little elf64-big elf32-little elf32-big plugin srec symbolsrec verilog tekhex binary ihex

$ powerpcle-linux-ar --help
 [...]
powerpcle-linux-ar: supported targets: elf32-powerpcle aixcoff-rs6000 elf32-powerpc ppcboot elf64-powerpc elf64-powerpcle elf64-little elf64-big elf32-little elf32-big plugin srec symbolsrec verilog tekhex binary ihex

quoted

Then again, does that work at *all* nowadays?  Do we even consider that
important, *should* it work?

Yes and yes. There were a lot of bugs in the kernel makefiles after we
added LE support which prevented a biarch/biendian compiler from working.
But now it does work and we want it to keep working because it means you
can have a single compiler for building 32-bit, 64-bit BE & 64-bit LE.

Good to hear :-)


Segher