On Tue, Dec 07, 2021 at 10:59:51AM -0700, Nathan Chancellor wrote:

When building with LLVM's integrated assembler, the build errors because
it does not implement -mfix-loongson2f-{jump,nop}:

arch/mips/loongson2ef/Platform:36: *** only binutils >= 2.20.2 have needed option -mfix-loongson2f-nop.  Stop.

The error is a little misleading because binutils are not being used in
this case.

To clear this up, remove the as-option calls because binutils 2.23 is
the minimum supported version for building the kernel. At the same time,
remove the cc-option calls for the '-march=' flags, as GCC 5.1.0 is the
minimum supported version.

This change will not fix the LLVM build for CONFIG_CPU_LOONGSON2{E,F},
as it does not implement the loongson2{e,f} march arguments (nor r4600,
so it will error prior to this change) nor the assembler flags mentioned
above but it will make the errors more obvious.

Link: https://github.com/ClangBuiltLinux/linux/issues/1529
Reported-by: Ryutaroh Matsumoto <redacted>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---

This dependency on certain toolchain flags should probably be moved into
Kconfig at some point so that users cannot select configurations that
they do not have support for so that their builds do not error. However,
from a brief survey, there is not a clean way to codify these
dependencies at the moment because the CPU configs are selected by the
individual machines that implement them, meaning that the dependencies
would need to be added to all the machine configs (as 'select ...'
overrides 'depends on ...'), which is outside the scope of this patch.
Furthermore, one could argue that it is better for the user to get a big
error when they are missing support for something, rather than the
configs getting disabled silently, especially if they are critical to
the machine.

 arch/mips/loongson2ef/Platform | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]