Add arm-linux support to delve

[puppywang]

This is the intial support of arm arch for linux os, to address the problem in this issue https://github.com/go-delve/delve/issues/20, The arm-linux's ptrace is lacking support of PTRACE_SINGLESTEP, so we need to emulate it by setup breakpoint at any possible next instructions, and then continue execution. I try to fix all the bug that I found, but there may still have plenty of them. Any code review comments is welcome, thanks.

[chainhelen]

So great.

[puppywang]

In a previous comment I was asking "How do we test this?". This is a question we need to find an answer to. We like to have continuous integration for the architectures we support.

Yes, currently I do only a little test on raspberry pi4, and I am looking for help to make a more coverage test, do we have any guideline to make such test on different platform? Thanks.

[aarzilli]

Yes, currently I do only a little test on raspberry pi4, and I am looking for help to make a more coverage test, do we have any guideline to make such test on different platform? Thanks.

So far we've gotten along using free services like travis, see .travis.yml. It doesn't have 32bit arm but I don't know if it's possible to do the same thing we do with linux/386.

[aarzilli]

Regarding testing this, I tried just adding an export GOARCH=arm to the build script. This works on my raspberry pi but it doesn't on Travis-CI, presumably because they didn't enable the appropriate kernel option. Result of the experiment here: https://github.com/go-delve/delve/pull/2218

Additionally the tests hang randomly on my raspberrypi inside native.(*nativeThread).singleStep.

[puppywang]

Additionally the tests hang randomly on my raspberrypi inside native.(*nativeThread).singleStep.

Got, let me check with my arm device.

[alexis-evelyn]

Can confirm d75633f5b1e444a876ede6ef99b77d845c98f443 works on my Raspberry Pi 3 with an armhf type processor.

[daresan]

So no success, to make delve work on a 32bit raspberry Pi OS yet? Just asking, because I just spent more than 2 hours trying to find a 32bit version for raspbian. It should be mentioned in the documentation.

[xcaptain]

Also got a raspberry pi and can't run dlv would take some time to try this branch and see if it works on raspberry pi 4b+

[puppywang]

Also got a raspberry pi and can't run dlv would take some time to try this branch and see if it works on raspberry pi 4b+

Before this merge is accept, you could try my working branch, try following cmd.

git clone https://github.com/puppywang/delve
cd delve
go install
``
And try debug with delve.

[krasi-georgiev]

magic I just tested it and it works!

[krasi-georgiev]

spoke too soon, stepping in almost never works.

[derekparker]

I've been holding off on a deeper review of this since we've never been able to answer the question of how do we have CI for this? I agree 32-bit ARM support would be great, but we need CI to verify this (I don't even have a Pi or other 32-bit ARM system to test this on, unfortunately).

[aarzilli]

@derekparker we could probably do the same thing we do on 386 and run it inside docker. If the kernel is compiled with compatibility with arm32 binaries the tests can be run directly on arm64. See my comment https://github.com/go-delve/delve/pull/2122#issuecomment-721048134. The problem however is that it randomly hangs inside singleStep.

[derekparker]

@derekparker we could probably do the same thing we do on 386 and run it inside docker. If the kernel is compiled with compatibility with arm32 binaries the tests can be run directly on arm64. See my comment #2122 (comment). The problem however is that it randomly hangs inside singleStep.

Ack, alright that makes sense.

@puppywang will you be able to investigate this outstanding issue?

[chrisdutz]

Another option I discovered recently would be to use a GitHub Action and to define a "local runner" ... there a RPi could possibly be setup as local runner.

[chrisdutz]

And to the cross compiling on a non-arm machine. Was having similar issues with cross compiling some Go application using CGO to 32bit mips and solved that by using a toolchain from the OpenWRT project and setting CC to a gcc version built for building mips. Currently I'm doing the same for an OpenWRT system intended for arm 32bit systems, so this could be used ... however building the OpenWRT toolchain does consume quite a bit of CI-time and might drain the resources an open-source project has available.

[krasi-georgiev]

or use the new Balena open fleet :)

https://www.balena.io/blog/introducing-open-fleets-and-self-submitted-apps-and-blocks-on-balenahub/?mc_cid=092773ae21#open-fleets

[chrisdutz]

So yesterday I successfully used what we use for building our application for arm32 devices and was able to compile the arm version on my normal ubuntu laptop (So it should be buildable on a normal CI agent or in a Docker container). I was able to run the Delve binary on my edge device, but yes ... I also did encounter these lockups.

Is there anything I can help with?

[jochen42]

i am using a patched dlv-binary (the code of the mr) and go 1.17 on linux-arm7 and remote-debugging. work's like charm until now. do you plan to integrate this into the stable binanry? Can i support?

[aarzilli]

i am using a patched dlv-binary (the code of the mr) and go 1.17 on linux-arm7 and remote-debugging. work's like charm until now. do you plan to integrate this into the stable binanry? Can i support?

Last time I looked at this it didn't pass most of the tests reliably, so there are no plans at the moment to merge this. If you want to rebase it and fix the problems yourself see: https://github.com/go-delve/delve/blob/master/Documentation/internal/portnotes.md

[derekparker]

Closing stale PR.