bug: update with module and fix empty struct

[vsoch]

Problem: the current version does not have a go module, and the build / run will fail with recent versions of go (cgo) that do not allow creating an empty struct. This is an attempt to fix that. I will need to test it to see if it actually works. I am also adding GitHub CI (to run go test) along with a VSCode developer container environment that has hwloc ready to go for easier development.

I'm going to do a quick test with my branch here (via a PR that specifies a different module path) and can report back.

[vsoch]

Ah I think I see the issues you were probably running into? Go doesn't like the static bit for a module:

/tmp/go-build/cgo-gcc-prolog:58: warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking

I tried building hwloc as a non static library, that doesn't work either.

make[3]: Entering directory '/opt/hwloc/utils/hwloc'
  CCLD     hwloc-annotate
/usr/bin/ld: attempted static link of dynamic object `/opt/hwloc/hwloc/.libs/libhwloc.so'
collect2: error: ld returned 1 exit status

I'll ping some of my colleagues and see if they have any ideas. We wanted to use this for a compatibility checking tool for applications and containers (for OCI) but seems like it might be the wrong tool if it's impossible to use.

[c0mm4nd]

Thanks for your great PR.

getaddrinfo warning is not from this lib or golang favor, it's from glibc xmrig/xmrig#238 (comment).

If you want to use libhwloc as a shared lib, suggest removing the lines like //#cgo LDFLAGS: -static -static-libgcc before go build.

[vsoch]

That worked! I've updated the PR here. Quick question for you - what is a "hello world" example for using this? I've been trying to do a basic init and then "print something out I can see" - my first effort the print segfaulted, and then I followed a pattern in a test and it doesn't segfault (but I don't see anything). I'm new to using hwloc outside of the command line tools so apologies for my naivete. Here is what I am testing:

	topo, err := hwloc.NewTopology()
	if err != nil {
		return info, err
	}
	err = topo.Load()
	if err != nil {
		return info, err
	}
	nodeSet := topo.HwlocGetNUMANodeObjByOSIndex(0)
	topo.HwlocSetMemBind(nodeSet, hwloc.HwlocMemBindBind, hwloc.HwlocMemBindThread|hwloc.HwlocMemBindByNodeSet)
	nodes, err := nodeSet.Values()
	if err != nil {
		return info, err
	}
	for _, node := range nodes {
		fmt.Println(node)
	}

I'm mostly looking to print out metadata / see what I have to work with.

[c0mm4nd]

To check the result of topo.HwlocSetMemBind, you can use HWLOC_DECLSPEC int hwloc_get_membind(hwloc_topology_t topology, hwloc_bitmap_t set, hwloc_membind_policy_t * policy, int flags); to get the policy (not implemented in go yet, but its easy).

[vsoch]

I'm generally interested in getting the equivalent output that I might get for lstopo or in the xml file generated - I'm not a C programmer so the "it's easy" part is probably not applicable here! 😆 Do you have examples / know someone that has used your library that might help me get started?

[c0mm4nd]

Sorry for replying late. This repo was used to enable NUMA support on GxMiner.

[vsoch]

No worries, and thanks! I will likely take a look in the next few weeks (just very busy this week).