Re: [RFC bpf-next 0/5] Convert iproute2 to use libbpf (WIP)

On 2/4/20 3:35 PM, Toke Høiland-Jørgensen wrote:

quoted

Most likely, making iproute2 use libbpf statically is going to be
challenging and I am not sure it is the right thing to do (unless the
user is building a static version of iproute2 commands).

Linking dynamically would imply a new dependency. I'm not necessarily
against that, but would it be acceptable from your PoV? And if so,
should we keep the current internal BPF code for when libbpf is not
available, or would it be acceptable to not be able to load BPF programs
if libbpf is not present (similar to how the libelf dependency works
today)?

iproute2 recently gained the libmnl dependency for extack. Seems like
libbpf falls into the similar category.

quoted

2. git submodules can be a PITA to deal with (e.g., jumping between
branches and versions), so there needs to be a good reason for it.

Yes, totally with you on that. Another option could be to just copy the
files into the iproute2 tree, and update them the same way the kernel
headers are? Or maybe doing fancy things like this:
https://github.com/apenwarr/git-subtrac

kernel uapi is a totally different reason to import the headers. bpf
functionality is an add-on.

I would like to see iproute2 work with libbpf. Given libbpf's current
status and availability across OS'es that is going to be a challenge for
a lot of OS'es which is why I suggested the HAVE_LIBBPF check falls back
to existing code if libbpf is not installed.

quoted

3. iproute2 code needs to build for a wide range of OSes and not lose
functionality compared to what it has today.

Could you be a bit more specific about "a wide range of OSes"? I guess
we could do the work to make sure libbpf builds on all the same
platforms iproute2 supports, but we'd need something a bit more definite
to go on...

rhel5/centos5? definitely rhel6/centos6 time frame and forward.

Stephen: has the backwards lifetime ever been stated?

Changing configure to check for existence and fall back to existing code
seems to me the safest option.