Hello Geert,
On Mon, 30 Dec 2024 09:53:29 +0100
Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
/usr/libexec/gcc/m68k-unknown-linux-musl/as -v -mcpu=68020 --pcrel -o a.o a.s
Thanks, so it fails when -mcpu=68040 is passed to the assembler.
Oh, I misread "caar" as "cacr". The latter exists on MC68040, the
former does not. However, that doesn't explain the failures for pflusha,
which is supported on 68040.
After disabling CONFIG_680[236]0 in the kernel config, I can build
it fine using the buildroot toolchain.
Conclusion: make sure your toolchain supports (a superset of) the
CPUs supported by your kernel config.
Thanks for the investigation. How should the toolchain be configured to
s upport multiple m68k CPUs? My understanding was that when you
configure gcc with --with-cpu=<something>, it means gcc will by default
emit code for <something>, but it can always be overridden when running
gcc using -mcpu=<somethingelse>.
How can one build this kernel/sys_m68k.c file if it uses instructions
that are mutually incompatible on different m68k cores?
Thomas
--
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
