Re: [PATCH 1/4] perf vendor events: Syntax corrections in Neoverse N1 json

[John Garry]

On 06/10/2021 09:43, James Clark wrote:

+ Andi

> On 05/10/2021 11:10, John Garry wrote:
> > On 04/10/2021 17:00, Andrew Kilroy wrote:
> > > There are some syntactical mistakes in the json files for the Cortex A76
> > > N1 (Neoverse N1).  This was obstructing parsing from an external tool.
> >
> > If the trailing comma is not allowed by standard, then maybe we should fix our parsing tool to not allow it also. However maybe there is a good reason why we allow it..
>
> It would be nice to do, because I have also made similar fixes before. We looked at the STRICT option
> in the parser (https://github.com/zserge/jsmn), but even then it seems to allow trailing commas.
>
> Trailing commas are not allowed in the json standard, but there is a split between parsers
> where some allow it and others don't. Specifically the Python parser doesn't allow it, and Python
> can easily be involved in some workflow that parses these files.
>
> The only way forwards I can think of is either getting a change accepted upstream to the parser
> and then updating it in perf, switching to a different parser, or doing some hack to add an extra
> step in perf to look for commas. None of which sound ideal.

Looking at the license in jsmn.c, we seem to be ok to modify it (to 
error on non-standard trailing ',') - that parser has already apparently 
been modified in mainline.

If we do that then I hope that there are not to many violations in out 
JSONs, including downstream.

Thanks,
John