LWN: Comments on "BPFd: Running BCC tools remotely across systems and architectures"

BPFd: Running BCC tools remotely across systems and architectures

_joel_ — Tue, 30 Jan 2018 02:45:21 +0000

It seems an extra effort and trying to fit something into LLDB or gdb-server, to do something that isn't supposed to. We're not remotely debugging a target process, not sure how well it really fits into a remote debugger model. Instead of that, you could consider contributing to BPFd and making it better ;D

BPFd: Running BCC tools remotely across systems and architectures

_joel_ — Tue, 30 Jan 2018 02:42:26 +0000

BPFd is not restricted to Android though. Further things not in libbpf may need to be performed as well on the remote side. Also its much simpler than LLDB ;-)

BPFd: Running BCC tools remotely across systems and architectures

alison — Mon, 29 Jan 2018 04:38:50 +0000

I see that there's an lldb-server:

http://lldb.llvm.org/remote.html

That seem to be the back-end of interest fot those of us not rinning Android on the remote target, but given a well-specofied protocol, perhaps it's just as easy to get gdbserver working? The task is to teach the server how to emit the libbpf commands.

BPFd: Running BCC tools remotely across systems and architectures

leoyan2017 — Fri, 26 Jan 2018 02:41:17 +0000

Thanks a lot, @chipb, @Joel. Will use github for later question and discussion.

BPFd: Running BCC tools remotely across systems and architectures

_joel_ — Fri, 26 Jan 2018 01:22:29 +0000

Thanks Karim!

> I glanced over the code quickly looking for logging and only found this
> "/* TODO: logging disabled for now, add mechanism in future */".
> Any plans on leaving traces in /data of the BPF operations conducted remotely?

Yes, this is something that we should do.

> Also, any chance of having local cache or already compiled scripts that could
> be run locally on the target? I can see the value of being able to leverage
> existing script sets locally while the device has already shipped and is no
> longer connected to a development system.

Yes, that could be done by enabling debugging (BCC_REMOTE_DEBUG) on the BCC side and getting the commands. Then inputting the commands to BPFd on the target. The issue though then is the presentation layer. Without BCC running on the host side, you can't interpret the maps and output data unless the target was running BCC itself. But yes, one could perform the loader functionality of eBPF just by purely using BPFd without any need for BCC (I mentioned this with an example in the article)

BPFd: Running BCC tools remotely across systems and architectures

_joel_ — Fri, 26 Jan 2018 01:17:47 +0000

Yes, its quite extensible so you can absolutely add a new 'ssh' remote to do that. Check how I did it for adb: https://github.com/joelagnel/bcc/tree/bcc-bpfd/src/python...

I created an issue here for this:
https://github.com/joelagnel/bpfd/issues/11

Feel free to send in a patch and let me know if you need any help! thanks!

BPFd: Running BCC tools remotely across systems and architectures

chipb — Thu, 25 Jan 2018 17:17:13 +0000

Without having looked at the code yet...

> With the process remote, which is probably just useful for local testing, BPFd is forked on the same machine running BCC and communicates with it over stdin and stdout.

...it sounds like this could be done by extending the ‘process’ remote to do something like fork “ssh targethost bpfd” instead. It might be configurable to do that already.

BPFd: Running BCC tools remotely across systems and architectures

karim — Wed, 24 Jan 2018 17:52:51 +0000

This is very cool. Happy to see efforts being done to get BPF running cross-platform. Architecture "independence" is one of the features that I liked of the ktap proposal (https://github.com/ktap/ktap).

I glanced over the code quickly looking for logging and only found this "/* TODO: logging disabled for now, add mechanism in future */". Any plans on leaving traces in /data of the BPF operations conducted remotely? This might have some value. Also, any chance of having local cache or already compiled scripts that could be run locally on the target? I can see the value of being able to leverage existing script sets locally while the device has already shipped and is no longer connected to a development system.

BPFd: Running BCC tools remotely across systems and architectures

leoyan2017 — Wed, 24 Jan 2018 14:35:38 +0000

Great work, Joel!

Can BPFd support ssh connection? If it can support ethernet/ssh connection, I'd like give a try with debian on Hikey :)

BPFd: Running BCC tools remotely across systems and architectures

_joel_ — Wed, 24 Jan 2018 01:42:43 +0000

Thanks a lot!

BPFd: Running BCC tools remotely across systems and architectures

kugel — Tue, 23 Jan 2018 19:36:14 +0000

This is really cool, looks extremely useful for my daily job as well.