Re: [PATCH] usb: gadget: functions: add ftrace export over USB

[Felipe Balbi]

Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes:

> Allow for ftrace data to be exported over a USB Gadget
> Controller. With this, we have a potentially very fast pipe for
> transmitting ftrace data to a Host PC for further analysis.
>
> Note that in order to decode the data, one needs access to kernel
> symbols in order to convert binary data into function names and what
> not.
>
> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
> ---
>
> I wanted to take this through the gadget tree, but there is a
> dependency with a previous patch of mine adding and extra argument to
> the ->write() function. Hoping someone else will take it.

just as an extra note here. In order for this to be really useful, it
would be nice to be able to control what is going to be traced over USB
as well, but that means exporting a few extra functions to GPL drivers.

Would that be okay? I could have a set of vendor-specific control
requests to set buffer size and to read/write ftrace filter functions.

The idea is that things like e.g. Android SDK could rely on this on
debug builds and the SDK itself would make sure to keep a copy of
vmlinux around to processing of the data coming through USB.

-- 
balbi

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