Hi Michael,
On 19/11/2021 09:29, Michael Olbrich wrote:
On Thu, Nov 18, 2021 at 03:32:04PM +0000, Ian Abbott wrote:
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):
It probably is added from here:
arch-$(CONFIG_CPU_32v7) :=-D__LINUX_ARM_ARCH__=7 $(call cc-option,-march=armv7-a,-march=armv5t -Wa$(comma)-march=armv7-a)
The check for -march=armv7-a fails for some reason so the fallback is used.
Yes, I showed the exact failure resulting from the cc-option call
further down my email:
cc1: error: ‘-mfloat-abi=hard’: selected architecture lacks an FPU
I've seen this when CC is a wrapper and already adds -mcpu=... to the
commandline. In that case gcc now complains about the combination and the
check fails.
In my case, CC was set by this "build.sh" script:
#! /bin/sh
SRC="../barebox-de0-nano-soc"
ARCH="arm"
CROSS_COMPILE=arm-linux-gnueabihf-
CC='$(CROSS_COMPILE)gcc-11'
make -C "$SRC" O=`pwd` ARCH="$ARCH" CROSS_COMPILE="$CROSS_COMPILE"
CC="$CC" $*
so after expansion, CC=arm-linux-gnueabihf-gcc-11
Michael
Cheers, Ian.
arch-$(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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