[U-Boot] [RFC PATCH 3/5] arm: Kconfig: Add entry for MMU

[Lokesh Vutla]

On Tuesday 24 April 2018 06:50 PM, Tom Rini wrote:
> On Tue, Apr 24, 2018 at 06:24:46PM +0530, Lokesh Vutla wrote:
> 
>> Add a Kconfig entry for MMU and imply for all platforms
>> using cache-cp15.c. Using imply instead of select so that
>> MMU can be disabled by defconfigs when not needed.
>>
>> Signed-off-by: Lokesh Vutla <lokeshvutla at ti.com>
>> ---
>>  arch/arm/Kconfig      | 15 +++++++++++++++
>>  arch/arm/lib/Makefile |  6 +-----
>>  2 files changed, 16 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> index de36ab6701..fe5bff097d 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -74,6 +74,12 @@ config ARM_ASM_UNIFIED
>>  config THUMB2_KERNEL
>>  	bool
>>  
>> +config MMU
>> +	bool "MMU-based Paged Memory Management Support"
>> +	help
>> +	  Select if you want MMU-based virtualised addressing space
>> +	  support by paged memory management.
>> +
>>  # If set, the workarounds for these ARM errata are applied early during U-Boot
>>  # startup. Note that in general these options force the workarounds to be
>>  # applied; no CPU-type/version detection exists, unlike the similar options in
>> @@ -158,33 +164,40 @@ config ARM_ERRATA_855873
>>  config CPU_ARM720T
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_ARM920T
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_ARM926EJS
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_ARM946ES
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_ARM1136
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_ARM1176
>>  	bool
>>  	select HAS_VBAR
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_V7
>>  	bool
>>  	select HAS_VBAR
>>  	select HAS_THUMB2
>>  	select SYS_CACHE_SHIFT_6
>> +	imply MMU
>>  
>>  config CPU_V7M
>>  	bool
>> @@ -200,10 +213,12 @@ config CPU_V7R
>>  config CPU_PXA
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config CPU_SA1100
>>  	bool
>>  	select SYS_CACHE_SHIFT_5
>> +	imply MMU
>>  
>>  config SYS_CPU
>>  	default "arm720t" if CPU_ARM720T
>> diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
>> index 3d3085e917..f907adc161 100644
>> --- a/arch/arm/lib/Makefile
>> +++ b/arch/arm/lib/Makefile
>> @@ -63,11 +63,7 @@ obj-y	+= reset.o
>>  endif
>>  
>>  obj-y	+= cache.o
>> -ifndef CONFIG_ARM64
>> -ifndef CONFIG_CPU_V7M
>> -obj-y	+= cache-cp15.o
>> -endif
>> -endif
>> +obj-$(CONFIG_MMU)	+= cache-cp15.o
>>  
>>  obj-y	+= psci-dt.o
> 
> So, funny enough.  We have CONFIG_MMU code in ARM today that I bet
> doesn't work and is just copy/pasted from the kernel and we should drop.
> 
> For right here, I think I'd rather see some CONFIG flag about
> CONFIG_SYS_ARM_CACHE_CP15 instead.

Sure will update it in next version.

Thanks and regards,
Lokesh