[PATCH v1 1/2] RISC-V: skip parsing multi-letter extensions starting with caps

[Yangyu Chen]

Hi,

On Wed, 26 Apr 2023 15:37:58 +0100, Conor Dooley wrote:
> Perhaps the thing to do is to actually take Yangyu's first patch and my
> second one, since the problem with backwards compatibility doesn't stop
> the kernel from being more permissive?

How about taking my first patch[1] since the ECR[2] mentioned that
the format of the ISA string is defined in the RISC-V unprivileged
specification? However, I think we still need to stop the parser if
some characters that the parser is not able to handle as Andrew Jones
mentioned in the previous mail[3]. In this case, we still need to add
some code to stop parsing if any error happens.

In my humble opinion, backward compatibility can be solved by backports
to LTS kernels. I think the better option is to allow using uppercase
letters in the device-tree document to make the parser coherent with
RISC-V ISA specification but recommend using all lowercase letters for
better backward compatibility.

[1] https://lore.kernel.org/all/tencent_63090269FF399AE30AC774848C344EF2F10A@qq.com/
[2] https://drive.google.com/file/d/1nP3nFiH4jkPMp6COOxP6123DCZKR-tia/view
[3] https://lore.kernel.org/all/d7t6nxmblmyqriogs4bxakpse3qc7pc6cczjnhmkpk4kjwvgcb@3aihh3erdn6p/

Thanks,
Yangyu Chen