Re: [RFC][PATCH] Export supported trace features in debugfs

[Alexei Starovoitov]

On Tue, Mar 12, 2019 at 11:07:14AM +0000, Qais Yousef wrote:
> eBPF tools like bcc-tools have hard time figuring out when features like
> raw_tracepoint are supported in the kernel on which we are running. At
> the moment a fragile mechanism of matching bpf_find_raw_tracepoint()
> function in /proc/kallsyms is used to find out whether raw tracepoints
> can be used or not. But when this function was renamed recently to
> bpf_get_raw_tracepoint() the tool started to fail to use raw
> tracepoints.
> 
> To help in providing a more reliable way to detect features like
> RAW_TRACEPOINT, add a new file in trace debugfs to export the supported
> features.
> 
> $cat /sys/kernel/debug/tracing/supported_features
> RAW_TRACEPOINT
> EXAMPLE_FEATURE_1
> EXAMPLE_FEATURE_2
> 
> Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx>

this type of attempts have been made in the past and we always rejected them.
Please use 'bpftool' instead that detects numerous bpf related features including raw_tp.
# bpftool feature probe|grep raw_tracepoint
eBPF program_type raw_tracepoint is available