xtensa: add kernel ABI selection to Kconfig
Add choice to use default or call0 ABI for the kernel code. If call0 ABI
is chosen add '-mabi=call0' to the flags. The toolchain support for this
option is rather new so only enable it when the compiler supports it.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index b324f67..cf03ed54 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -92,6 +92,9 @@
config CPU_LITTLE_ENDIAN
def_bool !CPU_BIG_ENDIAN
+config CC_HAVE_CALL0_ABI
+ def_bool $(success,test "$(shell,echo __XTENSA_CALL0_ABI__ | $(CC) -mabi=call0 -E -P - 2>/dev/null)" = 1)
+
menu "Processor type and features"
choice
@@ -250,6 +253,38 @@
If unsure, say N.
+choice
+ prompt "Kernel ABI"
+ default KERNEL_ABI_DEFAULT
+ help
+ Select ABI for the kernel code. This ABI is independent of the
+ supported userspace ABI and any combination of the
+ kernel/userspace ABI is possible and should work.
+
+ In case both kernel and userspace support only call0 ABI
+ all register windows support code will be omitted from the
+ build.
+
+ If unsure, choose the default ABI.
+
+config KERNEL_ABI_DEFAULT
+ bool "Default ABI"
+ help
+ Select this option to compile kernel code with the default ABI
+ selected for the toolchain.
+ Normally cores with windowed registers option use windowed ABI and
+ cores without it use call0 ABI.
+
+config KERNEL_ABI_CALL0
+ bool "Call0 ABI" if CC_HAVE_CALL0_ABI
+ help
+ Select this option to compile kernel code with call0 ABI even with
+ toolchain that defaults to windowed ABI.
+ When this option is not selected the default toolchain ABI will
+ be used for the kernel code.
+
+endchoice
+
config USER_ABI_CALL0
bool
diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile
index 725cd4c..5097caa 100644
--- a/arch/xtensa/Makefile
+++ b/arch/xtensa/Makefile
@@ -35,6 +35,10 @@
KBUILD_CFLAGS += -pipe -mlongcalls -mtext-section-literals
KBUILD_CFLAGS += $(call cc-option,-mforce-no-pic,)
KBUILD_CFLAGS += $(call cc-option,-mno-serialize-volatile,)
+ifneq ($(CONFIG_KERNEL_ABI_CALL0),)
+KBUILD_CFLAGS += -mabi=call0
+KBUILD_AFLAGS += -mabi=call0
+endif
KBUILD_AFLAGS += -mlongcalls -mtext-section-literals
