Support unified trace buffer instead of relayfs, since relay will be replaced by it.
I think there might be another plan that stap generates ftrace-plug-in tracer
instead of using ring-buffer directly.
*** Bug 9801 has been marked as a duplicate of this bug. ***
Let's assess whether the ring buffer widget, or the larger control
structures around it in ftrace, are relevant/useful to systemtap.
We need at least:
- access to the ftrace buffering stuff from modules
- the ring buffers need to contain formatted ascii, since that is what scripts
produce, and not rely on subsequent trace_iter printing like current ftrace
engines; maybe reuse ftrace_printk
- per-script trace files (instead of /debugfs/tracing/trace intermingled) ...
unless some goofy multiplexing is the only way
- probably no connection with the overall control switch
/tracing/tracing_enabled), since scripts come and go at any time
-DSTP_USE_RING_BUFFER does this.