Hi,
My Debian "testing" build system updated the default version of
arm-linux-gnueabihf-gcc from 10.x to 11.x. Building barebox in thumb-2
mode for an ARMv7 (it's a SoCFPGA) with this compiler fails with
assembler errors such as:
CC common/state/state_variables.o
{standard input}: Assembler messages:
{standard input}:1535: Error: selected processor does not support `rev
r3,r3' in Thumb mode
{standard input}:1576: Error: selected processor does not support `rev
r3,r3' in Thumb mode
Building in verbose mode (V=1) shows that "make" has selected the
compile flags `-march=armv5t -Wa,-march=armv7-a` instead of the usual
`-march=armv7-a`.
Looking a little deeper, all of the following lines in
"arch/arm/Makefile" are failing to select the first option and
defaulting to the second option (if any):
arch-$(CONFIG_CPU_64v8) := -D__LINUX_ARM_ARCH__=8 $(call
cc-option,-march=armv8-a)
arch-$(CONFIG_CPU_32v7) :=-D__LINUX_ARM_ARCH__=7 $(call
cc-option,-march=armv7-a,-march=armv5t -Wa$(comma)-march=armv7-a)
arch-$(CONFIG_CPU_32v6) :=-D__LINUX_ARM_ARCH__=6 $(call
cc-option,-march=armv6,-march=armv5t -Wa$(comma)-march=armv6)
arch-$(CONFIG_CPU_32v5) :=-D__LINUX_ARM_ARCH__=5 $(call
cc-option,-march=armv5te,-march=armv4t)
The error from the compiler is:
cc1: error: ‘-mfloat-abi=hard’: selected architecture lacks an FPU
(Note: the error is only shown after tweaking the `try-run` command in
"scripts/Kbuild.include" so that it does not send error output to
"/dev/null".)
That error seems to be a change in behaviour between GCC 10.x and GCC 11.x.
At the point in the Makefile that the error occurs, the `-msoft-float`
option has not been added to `KBUILD_CPPFLAGS` yet. That is done further
down the Makefile except for `CONFIG_CPU_V8`. I guess it needs to be
added somewhere before problematic lines in the Makefile. I'm not sure
if `-msoft-float` is also needed for 64-bit ARMv8, but the error
suggests it is required there too.
--
-=( Ian Abbott <abbotti@xxxxxxxxx> || MEV Ltd. is a company )=-
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