Commit bc7dea00 authored by Uwe Kleine-König's avatar Uwe Kleine-König
Browse files

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: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Message-Id: 1358162123-30113-1-git-send-email-u.kleine-koenig@pengutronix.de
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
parent b849a60e

arch/arm/Kconfig

+2 −1
Original line number Original line Diff line number Diff line
@@ -1656,8 +1656,9 @@ config HZ 
	default 100

	default 100





config THUMB2_KERNEL

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

	depends on CPU_V7 && !CPU_V6 && !CPU_V6K

	default y if CPU_THUMBONLY

	select AEABI

	select AEABI

	select ARM_ASM_UNIFIED

	select ARM_ASM_UNIFIED

	select ARM_UNWIND

	select ARM_UNWIND

arch/arm/kernel/head-nommu.S

+7 −1
Original line number Original line Diff line number Diff line
@@ -32,15 +32,21 @@ 
 * numbers for r1.

 * numbers for r1.

 *

 *

 */

 */

	.arm





	__HEAD

	__HEAD



#ifdef CONFIG_CPU_THUMBONLY

	.thumb

ENTRY(stext)

#else

	.arm

ENTRY(stext)

ENTRY(stext)





 THUMB(	adr	r9, BSYM(1f)	)	@ Kernel is always entered in ARM.

 THUMB(	adr	r9, BSYM(1f)	)	@ Kernel is always entered in ARM.

 THUMB(	bx	r9		)	@ If this is a Thumb-2 kernel,

 THUMB(	bx	r9		)	@ If this is a Thumb-2 kernel,

 THUMB(	.thumb			)	@ switch to Thumb now.

 THUMB(	.thumb			)	@ switch to Thumb now.

 THUMB(1:			)

 THUMB(1:			)

#endif





	setmode	PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode

	setmode	PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode

						@ and irqs disabled

						@ and irqs disabled

arch/arm/mm/Kconfig

+8 −1
Original line number Original line Diff line number Diff line
@@ -397,6 +397,13 @@ config CPU_V7 
	select CPU_PABRT_V7

	select CPU_PABRT_V7

	select CPU_TLB_V7 if MMU

	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.

# Figure out what processor architecture version we should be using.

# This defines the compiler instruction set which depends on the machine type.

# This defines the compiler instruction set which depends on the machine type.

config CPU_32v3

config CPU_32v3
@@ -608,7 +615,7 @@ config ARCH_DMA_ADDR_T_64BIT 
	bool

	bool





config ARM_THUMB

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

	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

	default y

	help

	help

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