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 -- balbi
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