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Commit 801bb21c authored by Jonathan Austin's avatar Jonathan Austin
Browse files

ARM: mpu: Allow enabling of the MPU via kconfig 



Allows the user to select MPU support when compiling for ARM processors
that support the PMSAv7.

This ensures that CONFIG_SMP depends on the MPU in the case that no MMU
is present.

CONFIG_SMP_ON_UP is not implemented for nommu, so introduce an MMU
dependency there.

Signed-off-by: default avatarJonathan Austin <jonathan.austin@arm.com>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
parent eb08375e

arch/arm/Kconfig

+2 −2
Original line number Original line Diff line number Diff line
@@ -1414,7 +1414,7 @@ config SMP 
	depends on CPU_V6K || CPU_V7

	depends on CPU_V6K || CPU_V7

	depends on GENERIC_CLOCKEVENTS

	depends on GENERIC_CLOCKEVENTS

	depends on HAVE_SMP

	depends on HAVE_SMP

	depends on MMU

	depends on MMU || ARM_MPU

	select USE_GENERIC_SMP_HELPERS

	select USE_GENERIC_SMP_HELPERS

	help

	help

	  This enables support for systems with more than one CPU. If you have

	  This enables support for systems with more than one CPU. If you have
@@ -1435,7 +1435,7 @@ config SMP 




config SMP_ON_UP

config SMP_ON_UP

	bool "Allow booting SMP kernel on uniprocessor systems (EXPERIMENTAL)"

	bool "Allow booting SMP kernel on uniprocessor systems (EXPERIMENTAL)"

	depends on SMP && !XIP_KERNEL

	depends on SMP && !XIP_KERNEL && MMU

	default y

	default y

	help

	help

	  SMP kernels contain instructions which fail on non-SMP processors.

	  SMP kernels contain instructions which fail on non-SMP processors.

arch/arm/Kconfig-nommu

+11 −0
Original line number Original line Diff line number Diff line
@@ -50,3 +50,14 @@ config REMAP_VECTORS_TO_RAM 
	  Otherwise, say 'y' here.  In this case, the kernel will require

	  Otherwise, say 'y' here.  In this case, the kernel will require

	  external support to redirect the hardware exception vectors to

	  external support to redirect the hardware exception vectors to

	  the writable versions located at DRAM_BASE.

	  the writable versions located at DRAM_BASE.



config ARM_MPU

       bool 'Use the ARM v7 PMSA Compliant MPU'

       default y

       help

         Some ARM systems without an MMU have instead a Memory Protection

         Unit (MPU) that defines the type and permissions for regions of

         memory.



         If your CPU has an MPU then you should choose 'y' here unless you

         know that you do not want to use the MPU.