Re: [Minios-devel] [PATCH v3 21/43] arm64: define the CALLEE_SAVED_REGISTERS

[Julien Grall <julien.grall@xxxxxxx>]

On 25/04/2018 18:33, Julien Grall wrote:
> Hi,
Hi,

> On 16/04/18 07:32, Huang Shijie wrote:
> > In the arm64, the callee-saved registers are x19 ~ x29.
> s/In the/On/.
>
> I think it would be good to mention where that convention comes from as 
> this is not very obvious for non-arm expert :). This convention is from 
> AAPCS64 [1].
Also, you want to explain why x19-x29. At first this is not obvious 
because the table call x29 "fp" and x19-x28 "callee-saved registers". It 
took me a bit to find in the spec the line saying "A subroutine 
invocation must preserve the contents of the registers r19-r29 and SP."
Cheers,

--
Julien Grall

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