[U-Boot] merge arm64 to arm

[FengHua]

> -----原始邮件-----
> 发件人: "Måns Rullgård" <mans at mansr.com>
> 发送时间: 2013年8月17日 星期六
> 收件人: FengHua <fenghua at phytium.com.cn>
> 抄送: "Måns Rullgård" <mans at mansr.com>, trini <trini at ti.com>, u-boot <u-boot at lists.denx.de>, "albert.u.boot" <albert.u.boot at aribaud.net>, scottwood <scottwood at freescale.com>
> 主题: Re: merge arm64 to arm
> 
> 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.

> -- 
> Måns Rullgård
> mans at mansr.com