On Tue, 02 Apr 2019 08:44:31 +0300 Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> wrote: > Hi, > > Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes: Hi Felipe, I somehow missed both your original email and this gentle reminder. > > Hi guys, > > > > I've been thinking about turning my f-trace.c USB function [1] into an > > implementation of the USB Debug Class [2]. In order to support all > > requests, I would need means to control parts of the tracing subsystem, > > for example enabling and disabling tracing, flushing the trace buffer, > > changing trace buffer size, choose which trace events to enable, etc. I believe a lot of these are already available. Also note, that Divya made it possible to have your own tracing instance for a module. > > > > Some of those functions (e.g. print_trace_line()) are available for > > things like trace_kdb.c [3], but they're not available for modules; > > i.e. they're not exported symbols. > > > > This will involve a rather large change to tracing subsystem however we > > could rely on such infrastructure for remote debugging of e.g. IVIs, > > phones, etc. > > > > The USB Debug Class already predicts the presence of JTAG access and > > Hardware tracing modules to be exported over USB. It also allows for > > GDB-type access. Adding our linux kernel tracing would make it into a > > complete tracing solution. > > > > In order to fully support this we would need, not only to expose some > > internal trace functions for modules, but I suppose the trace format > > would have to be slightly better defined so that it be decoded remotely > > give access to vmlinux. > > > > What do you guys think about this? Would this be something that folks > > would be interested in? Currently we can only export ftrace data, not > > trace events or anything else. Ideally we would export raw trace buffer > > entries to be decoded at a later moment. > > Let me know what changes are needed and we can work something out. Sorry for the delay, it appears I missed quite a bit of emails in this period :-/ -- Steve > > cheers > > > > [1] https://marc.info/?i=20190321094748.7031-1-felipe.balbi@xxxxxxxxxxxxxxx > > [2] https://www.usb.org/sites/default/files/documents/usb_debug_class_rev_1_0_final_0.pdf > > [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/trace/trace_kdb.c#n20 > > A gentle reminder here. >
