[Buildroot] [PATCH 1/1] arch: add support for RISC-V 64-bit (riscv64) architecture

[Mark Corbin]

On 04/09/18 09:51, Arnout Vandecappelle wrote:
>
>>>>> Provided this, I think we should not allow enabling/disabling RVA: we
>>>>> should assume it's always enabled.  
>>>> I will force the selection of RVA for now, but will still show it in the
>>>> architecture options. It is possible that it could be come optional at
>>>> some point in the future.  
>>>  I would keep the option and make it blind (i.e. remove the prompt).
>>>
>>>  Keep the conditions in the C library selection as well, of course. The comment
>>> will never be shown, but it's already there fo when the atomics extension does
>>> become optional.
>> Meh, I'm not so sure. Is it likely that glibc adds support for
>> platforms without the atomic operations ? I'm not so sure. So I'd
>> rather not support it all for now, and add it when/if that becomes
>> available.
>  I don't think it's likely that glibc will add support for non-atomic variants.
> I do think it's likely that uClibc will do that. When uClibc for riscv is added
> (and it supports non-atomic), we *do* want to see the comment for glibc.
>
>  However, I'm going to back off from my earlier position. The rule in Buildroot
> is: don't add anything that is not useful right away, only add it when it is
> actually going to be used.
>
>  The RVA option itself is used, but the comment isn't (it can never become
> visible). So drop the comment.
>
>
>> Perhaps we could make the option visible, but forcefully selected by
>> the BR2_riscv option, so that in practice it cannot be disabled.
>  Well, that was your original suggestion, and my suggestion was: make the option
> invisible. I really don't see the point of a user-visible option that you can't
> (de)select.
>
>  Regards,
>  Arnout

I'm in favour of a user-visible option that you can't disable...I like
the fact that I can see which optional architecture ISA extensions have
been selected/used to build the toolchain and filesystem (without having
to look in .config).

*** Instruction Set Extensions ***
[ ] Integer Multiplication and Division (M) (NEW)
-*- Atomic Instructions (A)
[ ] Single-precision Floating-point (F) (NEW)
[ ] Compressed Instructions (C) (NEW)

Regards

Mark
-- 
Mark Corbin
Embecosm Ltd.
https://www.embecosm.com