On 04/06/2016 02:56 PM, Rick Mann wrote: > What would I need to get/do to enable me to single-step through > kernel code on BBB/G? JTAG header, some kind of interface, and a > bunch of software installed on Ubuntu? Can anyone make specific > recommendations? Is it even possible?
On 04/06/2016 03:34 PM, Rick Mann wrote: > Thanks, John. I've tried printk and other logging, but it's virtually > impossible to trace something like audio, which spans many modules. If this is a latency problem, ftrace is probably your best bet, but function_graph and the other tracers can induce even more latency. I've had to write my own latency tracer on occasion to measure specific code paths (most recently with UART DMA timeouts from softirq latency). I cribbed the basic functionality from the irqsoff tracer; let me know if that's something you'd find useful. If you really need to single-step, KGDB can be made to work but there are some limitations, the most crucial being that kgdboc runs over the console so you can't debug earlier than when the built-in 8250 driver probes. That's like 3 secs into boot so lots of init has already happened. FWIW, I did push an earlycon OMAP bootconsole for v4.6 but -rc2 is early days, and there's already been one problem with MMC block device numbering. But if you're desperate and don't have access to JTAG, earlycon does printk() output from even before page table setup up to console initialization. Regards, Peter Hurley -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
