Re: [PATCH bpf-next] bpf: Add bpf_read_raw_record() helper

[Song Liu <songliubraving@fb.com>]

> On Aug 25, 2022, at 9:57 AM, Namhyung Kim <namhyung@kernel.org> wrote:
> 
> On Tue, Aug 23, 2022 at 10:32 PM John Fastabend
> <john.fastabend@gmail.com> wrote:
>> Namhyung Kim wrote:
>>> Ok, now I think that I can use a bpf-output sw event.  It would need
>>> another BPF program to write data to the event and the test program
>>> can read it from BPF using this helper. :)
>> 
>> Ah good idea. Feel free to carry my ACK to the v2 with the test.
> 
> Hmm.. it seems not to work because
> 1. bpf_output sw event doesn't have the overflow mechanism and it
>   doesn't call the bpf program.
> 2. even if I added it, it couldn't run due to the recursion protection by
>   bpf_prog_active.

How about we enable some raw record for a software event? Something not 
controlled by BPF?

If this doesn't work, a self test that only runs on some hardware is also
helpful. 

Thanks,
Song