[Buildroot] [PATCH 04/16] uclibc: Enable compile in thumb mode when selected
Arnout Vandecappelle
arnout at mind.be
Wed Mar 16 23:01:20 UTC 2016
On 03/16/16 22:43, Thomas Petazzoni wrote:
> From: Paul Enman <paul.enman at gmail.com>
>
> Until now, when thumb was selected with threads, we were forcing ARM
> mode to be used, to workaround some problems building uClibc with
> threads in Thumb mode. Also, we were never enabling Thumb mode in
> uClibc when Thumb2 was selected in the configuration.
>
> Therefore, this commit updates the uclibc.mk logic to:
>
> - Force ARM mode only when gcc 4.7 or 4.8 is selected with Thumb1 and
> threads. We also explicitly disable COMPILE_IN_THUMB_MODE when we
> fall in this situation. With newer gcc versions, starting 4.9, this
> problem is fixed and we can build uClibc in Thumb1 mode.
>
> - Enable COMPILE_IN_THUMB_MODE when Thumb1 or Thumb2 is selected. We
> need to disable context functions since they don't build in Thumb
> mode.
>
> - Disable COMPILE_IN_THUMB_MODE explicitly otherwise.
>
> This allows to build a Thumb2 toolchain on ARMv7-M for example.
Principle looks OK to me, but it will of course have to be reworked if you
follow my suggestion os removing BR2_ARM_INSTRUCTIONS_THUMB2.
>
> Signed-off-by: Paul Enman <paul.enman at gmail.com>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> ---
> package/uclibc/uclibc.mk | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/package/uclibc/uclibc.mk b/package/uclibc/uclibc.mk
> index 88a4a8c..ce706e0 100644
> --- a/package/uclibc/uclibc.mk
> +++ b/package/uclibc/uclibc.mk
> @@ -75,9 +75,23 @@ define UCLIBC_ARM_ABI_CONFIG
> $(call KCONFIG_ENABLE_OPT,CONFIG_ARM_EABI,$(@D)/.config)
> endef
>
> -# Thumb build is broken with threads, build in ARM mode
> -ifeq ($(BR2_ARM_INSTRUCTIONS_THUMB)$(BR2_TOOLCHAIN_HAS_THREADS),yy)
> +# Thumb1 build is broken with threads with old gcc versions (4.7 and
> +# 4.8). Since all cores supporting Thumb1 also support ARM, we use ARM
> +# code in this case.
> +ifeq ($(BR2_GCC_VERSION_4_7_X)$(BR2_GCC_VERSION_4_8_X):$(BR2_ARM_INSTRUCTIONS_THUMB)$(BR2_TOOLCHAIN_HAS_THREADS),y:yy)
This would need to become something like
ifeq
($(BR2_GCC_VERSION_4_7_X)$(BR2_GCC_VERSION_4_8_X):$(BR2_ARM_INSTRUCTIONS_THUMB):$(BR2_ARM_CPU_HAS_THUMB2):$(BR2_TOOLCHAIN_HAS_THREADS),y:y::y)
But that is horrible, so some auxiliary variables should be introduced.
Or actually, it could be
ifeq ($(BR2_ARM_INSTRUCTIONS_THUMB),y)
ifeq
($(BR2_GCC_VERSION_4_7_X)$(BR2_GCC_VERSION_4_8_X):$(BR2_ARM_CPU_HAS_THUMB2):$(BR2_TOOLCHAIN_HAS_THREADS),y::y)
...arm...
else
...thumb...
endif
else
...arm...
endif
Regards,
Arnout
> UCLIBC_EXTRA_CFLAGS += -marm
> +define UCLIBC_ARM_THUMB_CONFIG
> + $(call KCONFIG_DISABLE_OPT,COMPILE_IN_THUMB_MODE,$(@D)/.config)
> +endef
> +else ifeq ($(BR2_ARM_INSTRUCTIONS_THUMB)$(BR2_ARM_INSTRUCTIONS_THUMB2),y)
> +define UCLIBC_ARM_THUMB_CONFIG
> + $(call KCONFIG_ENABLE_OPT,COMPILE_IN_THUMB_MODE,$(@D)/.config)
> + $(call KCONFIG_DISABLE_OPT,UCLIBC_HAS_CONTEXT_FUNCS,$(@D)/.config)
> +endef
> +else
> +define UCLIBC_ARM_THUMB_CONFIG
> + $(call KCONFIG_DISABLE_OPT,COMPILE_IN_THUMB_MODE,$(@D)/.config)
> +endef
> endif
>
> ifeq ($(BR2_UCLIBC_ARM_BX),y)
> @@ -362,6 +376,7 @@ define UCLIBC_KCONFIG_FIXUP_CMDS
> $(UCLIBC_ARC_TYPE_CONFIG)
> $(UCLIBC_ARC_PAGE_SIZE_CONFIG)
> $(UCLIBC_ARM_ABI_CONFIG)
> + $(UCLIBC_ARM_THUMB_CONFIG)
> $(UCLIBC_ARM_BX_CONFIG)
> $(UCLIBC_MIPS_ABI_CONFIG)
> $(UCLIBC_MIPS_ISA_CONFIG)
>
--
Arnout Vandecappelle arnout at mind be
Senior Embedded Software Architect +32-16-286500
Essensium/Mind http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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