diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2011-12-09 20:52:10 +0100 |
|---|---|---|
| committer | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2013-01-31 21:44:46 +0100 |
| commit | bc7dea00a9a0ea385bbc4aed67dfdcf7d8879953 (patch) | |
| tree | 242257c7c0a016595b672b3151abdf71ec5745a2 | |
| parent | b849a60e0903b1c5430c3859864554662e127a8d (diff) | |
ARM: let CPUs not being able to run in ARM mode enter in THUMB mode
Some ARM cores are not capable to run in ARM mode (e.g. Cortex-M3). So
obviously these cannot enter the kernel in ARM mode. Make an exception
for them and let them enter in THUMB mode.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Message-Id: 1358162123-30113-1-git-send-email-u.kleine-koenig@pengutronix.de
Acked-by: Nicolas Pitre <nico@linaro.org>
| -rw-r--r-- | arch/arm/Kconfig | 3 | ||||
| -rw-r--r-- | arch/arm/kernel/head-nommu.S | 8 | ||||
| -rw-r--r-- | arch/arm/mm/Kconfig | 9 |
3 files changed, 17 insertions, 3 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 67874b82a4ed..e04c7793f47e 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1656,8 +1656,9 @@ config HZ default 100 config THUMB2_KERNEL - bool "Compile the kernel in Thumb-2 mode" + bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY depends on CPU_V7 && !CPU_V6 && !CPU_V6K + default y if CPU_THUMBONLY select AEABI select ARM_ASM_UNIFIED select ARM_UNWIND diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S index 2c228a07e58c..6a2e09c952c7 100644 --- a/arch/arm/kernel/head-nommu.S +++ b/arch/arm/kernel/head-nommu.S @@ -32,15 +32,21 @@ * numbers for r1. * */ - .arm __HEAD + +#ifdef CONFIG_CPU_THUMBONLY + .thumb +ENTRY(stext) +#else + .arm ENTRY(stext) THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM. THUMB( bx r9 ) @ If this is a Thumb-2 kernel, THUMB( .thumb ) @ switch to Thumb now. THUMB(1: ) +#endif setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode @ and irqs disabled diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 3fd629d5a513..8defd638c79e 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -397,6 +397,13 @@ config CPU_V7 select CPU_PABRT_V7 select CPU_TLB_V7 if MMU +config CPU_THUMBONLY + bool + # There are no CPUs available with MMU that don't implement an ARM ISA: + depends on !MMU + help + Select this if your CPU doesn't support the 32 bit ARM instructions. + # Figure out what processor architecture version we should be using. # This defines the compiler instruction set which depends on the machine type. config CPU_32v3 @@ -608,7 +615,7 @@ config ARCH_DMA_ADDR_T_64BIT bool config ARM_THUMB - bool "Support Thumb user binaries" + bool "Support Thumb user binaries" if !CPU_THUMBONLY depends on CPU_ARM720T || CPU_ARM740T || CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM940T || CPU_ARM946E || CPU_ARM1020 || CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_V6 || CPU_V6K || CPU_V7 || CPU_FEROCEON default y help |