From mboxrd@z Thu Jan 1 00:00:00 1970 From: nathan_lynch@mentor.com (Nathan Lynch) Date: Wed, 8 Apr 2015 16:41:05 -0500 Subject: [PATCH] ARM: VDSO: depend on CPU_V7 Message-ID: <1428529265-26772-1-git-send-email-nathan_lynch@mentor.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org (Arnd reported a build break with the VDSO code when targeting v4 (but not v4t). I haven't been able to recreate it locally because all the toolchains I have at hand convert 'bx lr' to 'mov pc,lr' when targeting v4.) The __get_datapage routine in the VDSO uses 'bx lr' to return to the caller. This is inappropriate when targeting v4 CPUs, and the VDSO is unlikely to be useful for pre-v7 CPUs anyway due to its reliance on the generic timers extension, so the easy thing to do here is just make CONFIG_VDSO depend on CONFIG_CPU_V7. An alternative considered was to use 'ldr pc,lr' when armv4 (or lower) is enabled, but Arnd pointed out that this would be broken when running with a kernel that supports both v4 arnd v4t, and you have a thumb user space. Reported-by: Arnd Bergmann Signed-off-by: Nathan Lynch --- arch/arm/mm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index b7644310236b..b4f92b9a13ac 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -827,7 +827,7 @@ config KUSER_HELPERS config VDSO bool "Enable VDSO for acceleration of some system calls" - depends on AEABI && MMU + depends on AEABI && MMU && CPU_V7 default y if ARM_ARCH_TIMER select GENERIC_TIME_VSYSCALL help -- 1.9.3