Hi, Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes: > 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. > > 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. > > 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. -- balbi
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