[U-Boot] merge arm64 to arm

Tom Rini trini at ti.com
Mon Aug 19 14:20:19 CEST 2013


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On 08/18/2013 11:46 PM, Sharma Bhupesh-B45370 wrote:
> [Re-posting as original msg was rejected due to HTML content..]
> 
>>> FengHua <fenghua at phytium.com.cn> writes:
>>> 
>>>>> FengHua <fenghua at phytium.com.cn> writes:
>>>>> 
>>>>>> hi tom, hi albert, yes, it's right. the u-boot could be 
>>>>>> more uniformly and maintainable if merging armv8 to arm 
>>>>>> architecture. I will try to migrate arm64 to armv8 
>>>>>> subarchitecture of arm. do you have any other advice?
>>>>> 
>>>>> Why?  The architectures are vastly different, arm64 
>>>>> (aarch64) being only loosely inspired by the 32-bit arm. It
>>>>> is not like with x86/amd64 where a lot of code can be 
>>>>> shared.
>>>> 
>>>> Of course, with a seperated architecture the arm64 code will 
>>>> be clear and simple. when it merged with arm a few file 
>>>> should be duplicated with the name "_v8" appended and many 
>>>> macro switch should be added. but most of the code will be
>>>> in armv8 directory which paralleled with armv7. it seems
>>>> that this implementation are more nice.
>>> 
>>> ARMv8 defines both a 32-bit (aarch32) and a 64-bit (aarch64) 
>>> instruction set.  The naming you are suggesting would be 
>>> misleading.
>>> 
>> 
>> aarch32 state is compatible with armv7. armv8 directory only 
>> provide aarch64 state support. as you said, it would be a little 
>> misleading.
>> 
> 
> ARMv8 ARM (Architecture Reference Manual) mentions that the ARMv8 
> architecture has support for both AArch32 and AArch64 and the ARM 
> can switch b/w the two instruction sets via exceptions.
> 
> So, whether choosing a naming convention similar to linux 
> (arch/arm64) would be more suitable is something to consider (even 
> though some of the files might be a copy of what is available in 
> arch/arm/cpu/armv7)?

I think we'll see what happens with a single directory first.  We
aren't talking about a binary that has to work on all cases (right
now...) and we want to avoid massive duplication of all of the C code
that really won't change.

- -- 
Tom
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