tracing: Allow mmio tracer to display trace_printk() and other events

Date: Sat Feb 27 2016 - 16:32:12 EST


I am trying to print trace markers from inside the kernel using the mmio-tracer's
mmiotrace_printk routine but it doesn't get printed. Looking back, i found this thread
and applied the said patch but that didn't work either.

Thereafter, I followed the code path starting at mmiotrace_printk which lead to __trace_array_vprintk
and in there,

tbuffer = get_trace_buf();
if (!tbuffer) {
/* pr_info("invalid buffer.\n"); */
len = 0;
goto out;

tbuffer turns out to be null which is why the call to mmiotrace_printk returns without printing my marker.

Has this been fixed or looked into ? Any help would be much appreciated.

Sanketh Nalli
College of Letters and Sciences
University of Wisconsin - Madison