@@ -679,7 +679,7 @@ config ARCH_DMA_ADDR_T_64BIT
bool
config ARM_THUMB
- bool "Support Thumb user binaries" if !CPU_THUMBONLY
+ bool "Support Thumb user binaries" if !CPU_THUMBONLY && EXPERT
depends on CPU_THUMB_CAPABLE
default y
help
@@ -690,6 +690,10 @@ config ARM_THUMB
instruction set resulting in smaller binaries at the expense of
slightly less efficient code.
+ If this option is disabled, and you run userspace that switches to
+ Thumb mode, signal handling will not work correctly, resulting in
+ segmentation faults or illegal instruction aborts.
+
If you don't know what this all is, saying Y is a safe choice.
config ARM_THUMBEE
David Mosberger reports random segfaults and other problems when running his buildroot userspace. It turns out that his kernel did not have support for Thumb userspace, nor did his application, but glibc made use of Thumb instructions in glibc. The kernel Thumb support option already recommends being enabled, and is also so biased, but clearly this is not enough of a recommendation. So, hide this behind CONFIG_EXPERT as well, and include a note to indicate the potential issues if it's turned off and userspace Thumb mode is made use of. Reported-by: David Mosberger <davidm@egauge.net> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> --- arch/arm/mm/Kconfig | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)