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ARM: let CPUs not being able to run in ARM mode enter in THUMB mode

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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>
This commit is contained in:
Uwe Kleine-König 2011-12-09 20:52:10 +01:00
parent b849a60e09
commit bc7dea00a9
3 changed files with 17 additions and 3 deletions
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3
arch/arm/Kconfig
View File

@ -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

8
arch/arm/kernel/head-nommu.S
View File

@ -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

9
arch/arm/mm/Kconfig
View File

@ -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