ARM: drop cc-option fallbacks for architecture selection
Subsystems (2)
PATCH 1/1 ARM: drop cc-option fallbacks for architecture selection
From: Arnd Bergmann <[email protected]>
Naresh and Antonio ran into a build failure with latest Debian armhf compilers, with lots of output like
tmp/ccY3nOAs.s:2215: Error: selected processor does not support `cpsid i' in ARM mode
As it turns out, $(cc-option) fails early here when the FPU is not selected before CPU architecture is selected, as the compiler option check runs before enabling -msoft-float, which causes a problem when testing a target architecture level without an FPU:
cc1: error: '-mfloat-abi=hard': selected architecture lacks an FPU
Passing e.g. -march=armv6k+fp in place of -march=armv6k would avoid this issue, but the fallback logic is already broken because all supported compilers (gcc-5 and higher) are much more recent than these options, and building with -march=armv5t as a fallback no longer works.
The best way forward that I see is to just remove all the checks, which also has the nice side-effect of slightly improving the startup time for 'make'.
The -mtune=marvell-f option was apparently never supported by any mainline compiler, and the custom Codesourcery gcc build that did support is now too old to build kernels, so just use -mtune=xscale unconditionally for those.
This should be safe to apply on all stable kernels, and will be required in order to keep building them with gcc-11 and higher.
--- arch/arm/Makefile | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)
arch/arm/Makefile +11 -11
@@ -60,15 +60,15 @@ KBUILD_CFLAGS += $(call cc-option,-fno-ipa-sra) # Note that GCC does not numerically define an architecture version # macro, but instead defines a whole series of macros which makes # testing for a specific architecture or later rather impossible. -arch-$(CONFIG_CPU_32v7M) =-D__LINUX_ARM_ARCH__=7 -march=armv7-m -Wa,-march=armv7-m -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-$(CONFIG_CPU_32v7M) =-D__LINUX_ARM_ARCH__=7 -march=armv7-m +arch-$(CONFIG_CPU_32v7) =-D__LINUX_ARM_ARCH__=7 -march=armv7-a +arch-$(CONFIG_CPU_32v6) =-D__LINUX_ARM_ARCH__=6 -march=armv6 # Only override the compiler option if ARMv6. The ARMv6K extensions are # always available in ARMv7 ifeq ($(CONFIG_CPU_32v6),y) -arch-$(CONFIG_CPU_32v6K) =-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6k,-march=armv5t -Wa$(comma)-march=armv6k) +arch-$(CONFIG_CPU_32v6K) =-D__LINUX_ARM_ARCH__=6 -march=armv6k endif -arch-$(CONFIG_CPU_32v5) =-D__LINUX_ARM_ARCH__=5 $(call cc-option,-march=armv5te,-march=armv4t) +arch-$(CONFIG_CPU_32v5) =-D__LINUX_ARM_ARCH__=5 -march=armv5te arch-$(CONFIG_CPU_32v4T) =-D__LINUX_ARM_ARCH__=4 -march=armv4t arch-$(CONFIG_CPU_32v4) =-D__LINUX_ARM_ARCH__=4 -march=armv4 arch-$(CONFIG_CPU_32v3) =-D__LINUX_ARM_ARCH__=3 -march=armv3m
@@ -82,7 +82,7 @@ tune-$(CONFIG_CPU_ARM720T) =-mtune=arm7tdmi tune-$(CONFIG_CPU_ARM740T) =-mtune=arm7tdmi tune-$(CONFIG_CPU_ARM9TDMI) =-mtune=arm9tdmi tune-$(CONFIG_CPU_ARM940T) =-mtune=arm9tdmi -tune-$(CONFIG_CPU_ARM946E) =$(call cc-option,-mtune=arm9e,-mtune=arm9tdmi) +tune-$(CONFIG_CPU_ARM946E) =-mtune=arm9e tune-$(CONFIG_CPU_ARM920T) =-mtune=arm9tdmi tune-$(CONFIG_CPU_ARM922T) =-mtune=arm9tdmi tune-$(CONFIG_CPU_ARM925T) =-mtune=arm9tdmi
@@ -90,11 +90,11 @@ tune-$(CONFIG_CPU_ARM926T) =-mtune=arm9tdmi tune-$(CONFIG_CPU_FA526) =-mtune=arm9tdmi tune-$(CONFIG_CPU_SA110) =-mtune=strongarm110 tune-$(CONFIG_CPU_SA1100) =-mtune=strongarm1100 -tune-$(CONFIG_CPU_XSCALE) =$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale -tune-$(CONFIG_CPU_XSC3) =$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale -tune-$(CONFIG_CPU_FEROCEON) =$(call cc-option,-mtune=marvell-f,-mtune=xscale) -tune-$(CONFIG_CPU_V6) =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm) -tune-$(CONFIG_CPU_V6K) =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm) +tune-$(CONFIG_CPU_XSCALE) =-mtune=xscale +tune-$(CONFIG_CPU_XSC3) =-mtune=xscale +tune-$(CONFIG_CPU_FEROCEON) =-mtune=xscale +tune-$(CONFIG_CPU_V6) =-mtune=arm1136j-s +tune-$(CONFIG_CPU_V6K) =-mtune=arm1136j-s # Evaluate tune cc-option calls now tune-y := $(tune-y)
Signature · 1 line
2.29.2
On 2021-10-18 16:07:12 [+0200], Arnd Bergmann wrote:
…
Quoted 9 lines
Passing e.g. -march=armv6k+fp in place of -march=armv6k would avoid this issue, but the fallback logic is already broken because all supported compilers (gcc-5 and higher) are much more recent than these options, and building with -march=armv5t as a fallback no longer works.
The best way forward that I see is to just remove all the checks, which also has the nice side-effect of slightly improving the startup time for 'make'.
…
Quoted 2 lines
This should be safe to apply on all stable kernels, and will be required in order to keep building them with gcc-11 and higher.
Yes, please.
Quoted 7 lines
Reported-by Antonio Terceiro <[email protected]>Reported-by Naresh Kamboju <[email protected]>Reported-by Sebastian Andrzej Siewior <[email protected]>Cc Matthias Klose <[email protected]>Signed-off-by Arnd Bergmann <[email protected]>
Just booted Debian 9/ Stretch which ships
gcc version 6.3.0 20170516 (Debian 6.3.0-18)
to confirm that it fails to compile with the armv5t fallback.
Sebastian
Quoted 6 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
Naresh and Antonio ran into a build failure with latest Debian armhf compilers, with lots of output like
tmp/ccY3nOAs.s:2215: Error: selected processor does not support `cpsid i' in ARM mode
I just had exactly the same problem, and this patch fixes it for me as well. Compile- and run-tested with gcc-11 (Debian 11.2.0-10) armhf & Linux 5.15.0
On 2021-10-18 16:07:12 [+0200], Arnd Bergmann wrote:
…
Quoted 3 lines
This should be safe to apply on all stable kernels, and will be required in order to keep building them with gcc-11 and higher.
Could we get this applied, please?
Matthias Klose asked gcc-upstream if the change, causing the problem, was expected/ intended. I don't think this matters given that the provided fallback does not work.
Sebastian
Hi,
Quoted 31 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
Naresh and Antonio ran into a build failure with latest Debian armhf compilers, with lots of output like
tmp/ccY3nOAs.s:2215: Error: selected processor does not support `cpsid i' in ARM modeAs it turns out, $(cc-option) fails early here when the FPU is not selected before CPU architecture is selected, as the compiler option check runs before enabling -msoft-float, which causes a problem when testing a target architecture level without an FPU:
cc1: error: '-mfloat-abi=hard': selected architecture lacks an FPU
Passing e.g. -march=armv6k+fp in place of -march=armv6k would avoid this issue, but the fallback logic is already broken because all supported compilers (gcc-5 and higher) are much more recent than these options, and building with -march=armv5t as a fallback no longer works.
The best way forward that I see is to just remove all the checks, which also has the nice side-effect of slightly improving the startup time for 'make'.
The -mtune=marvell-f option was apparently never supported by any mainline compiler, and the custom Codesourcery gcc build that did support is now too old to build kernels, so just use -mtune=xscale unconditionally for those.
This should be safe to apply on all stable kernels, and will be required in order to keep building them with gcc-11 and higher.
Quoted 8 lines
Reported-by Antonio Terceiro <[email protected]>Reported-by Naresh Kamboju <[email protected]>Reported-by Sebastian Andrzej Siewior <[email protected]>Cc Matthias Klose <[email protected]>Signed-off-by Arnd Bergmann <[email protected]>---
Thanks, I ran into this issue after affected gcc release migrated to Debian testing. The patch makes the kernel compile again:
Would be great if this could become part of 5.16-rc1, which is usually used as base by subsystem maintainers.
Thanks,
-- Sebastian
Quoted 57 lines
arch/arm/Makefile | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)arch/arm/Makefile +11
-11@@ -60,15 +60,15 @@ KBUILD_CFLAGS += $(call cc-option,-fno-ipa-sra) # Note that GCC does not numerically define an architecture version # macro, but instead defines a whole series of macros which makes # testing for a specific architecture or later rather impossible. -arch-$(CONFIG_CPU_32v7M) =-D__LINUX_ARM_ARCH__=7 -march=armv7-m -Wa,-march=armv7-m -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-$(CONFIG_CPU_32v7M) =-D__LINUX_ARM_ARCH__=7 -march=armv7-m +arch-$(CONFIG_CPU_32v7) =-D__LINUX_ARM_ARCH__=7 -march=armv7-a +arch-$(CONFIG_CPU_32v6) =-D__LINUX_ARM_ARCH__=6 -march=armv6 # Only override the compiler option if ARMv6. The ARMv6K extensions are # always available in ARMv7 ifeq ($(CONFIG_CPU_32v6),y) -arch-$(CONFIG_CPU_32v6K) =-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6k,-march=armv5t -Wa$(comma)-march=armv6k) +arch-$(CONFIG_CPU_32v6K) =-D__LINUX_ARM_ARCH__=6 -march=armv6k endif -arch-$(CONFIG_CPU_32v5) =-D__LINUX_ARM_ARCH__=5 $(call cc-option,-march=armv5te,-march=armv4t) +arch-$(CONFIG_CPU_32v5) =-D__LINUX_ARM_ARCH__=5 -march=armv5te arch-$(CONFIG_CPU_32v4T) =-D__LINUX_ARM_ARCH__=4 -march=armv4t arch-$(CONFIG_CPU_32v4) =-D__LINUX_ARM_ARCH__=4 -march=armv4 arch-$(CONFIG_CPU_32v3) =-D__LINUX_ARM_ARCH__=3 -march=armv3m@@ -82,7 +82,7 @@ tune-$(CONFIG_CPU_ARM720T) =-mtune=arm7tdmi tune-$(CONFIG_CPU_ARM740T) =-mtune=arm7tdmi tune-$(CONFIG_CPU_ARM9TDMI) =-mtune=arm9tdmi tune-$(CONFIG_CPU_ARM940T) =-mtune=arm9tdmi -tune-$(CONFIG_CPU_ARM946E) =$(call cc-option,-mtune=arm9e,-mtune=arm9tdmi) +tune-$(CONFIG_CPU_ARM946E) =-mtune=arm9e tune-$(CONFIG_CPU_ARM920T) =-mtune=arm9tdmi tune-$(CONFIG_CPU_ARM922T) =-mtune=arm9tdmi tune-$(CONFIG_CPU_ARM925T) =-mtune=arm9tdmi@@ -90,11 +90,11 @@ tune-$(CONFIG_CPU_ARM926T) =-mtune=arm9tdmi tune-$(CONFIG_CPU_FA526) =-mtune=arm9tdmi tune-$(CONFIG_CPU_SA110) =-mtune=strongarm110 tune-$(CONFIG_CPU_SA1100) =-mtune=strongarm1100 -tune-$(CONFIG_CPU_XSCALE) =$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale -tune-$(CONFIG_CPU_XSC3) =$(call cc-option,-mtune=xscale,-mtune=strongarm110) -Wa,-mcpu=xscale -tune-$(CONFIG_CPU_FEROCEON) =$(call cc-option,-mtune=marvell-f,-mtune=xscale) -tune-$(CONFIG_CPU_V6) =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm) -tune-$(CONFIG_CPU_V6K) =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm) +tune-$(CONFIG_CPU_XSCALE) =-mtune=xscale +tune-$(CONFIG_CPU_XSC3) =-mtune=xscale +tune-$(CONFIG_CPU_FEROCEON) =-mtune=xscale +tune-$(CONFIG_CPU_V6) =-mtune=arm1136j-s +tune-$(CONFIG_CPU_V6K) =-mtune=arm1136j-s # Evaluate tune cc-option calls now tune-y := $(tune-y)Signature · 1 line
2.29.2
Quoted 8 lines · Sebastian Reichel
Thanks, I ran into this issue after affected gcc release migrated to Debian testing. The patch makes the kernel compile again:
Tested-by Sebastian Reichel <[email protected]>Would be great if this could become part of 5.16-rc1, which is usually used as base by subsystem maintainers.
I've added it to Russell's patch tracker now as
https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9156/1
Arnd
Hi,
Quoted 6 lines · Arnd Bergmann
Quoted 4 lines · Sebastian Reichel
Thanks, I ran into this issue after affected gcc release migrated to Debian testing. The patch makes the kernel compile again:
Quoted 8 lines
Quoted 4 lines
Tested-by Sebastian Reichel <[email protected]>Would be great if this could become part of 5.16-rc1, which is usually used as base by subsystem maintainers.
I've added it to Russell's patch tracker now as
https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9156/1
Thanks.
FWIW, we uploaded in Debian 5.15.1 to experimental with the patch
applied, and the builds pass now: https://buildd.debian.org/status/logs.php?pkg=linux&arch=armhf
Regards,
Salvatore