On Thu, Mar 25, 2021 at 1:01 PM Rafael David Tinoco <rafaeldtinoco@xxxxxxxxxx> wrote: > > >> Unfortunately some distros don't have their kernel version defined > >> accurately in <linux/version.h> due to different long term support > >> reasons. > >> > >> It is important to have a way to override the bpf kern_version > >> attribute during runtime: some old kernels might still check for > >> kern_version attribute during bpf_prog_load(). > >> > >> Signed-off-by: Rafael David Tinoco <rafaeldtinoco@xxxxxxxxxx> > >> --- > >> tools/lib/bpf/libbpf.c | 10 ++++++++++ > >> tools/lib/bpf/libbpf.h | 1 + > >> tools/lib/bpf/libbpf.map | 1 + > >> 3 files changed, 12 insertions(+) > >> > > > > Hi Andrii and Rafael, > > > > Did you consider making kernel version an attribute of the load > > API, bpf_prog_load_xattr()? This feels slightly more natural > > to me, to tell the API the kernel you need at load time. > > Hi John, > > This is how I'm using: > https://github.com/rafaeldtinoco/portablebpf/blob/master/mine.c#L285 > > > Although, I don't use the skeleton pieces so maybe it would be > > awkward for that usage. > > having a xxx_bpf object: > > xxx_bpf__open_and_load() -> xxx_bpf__load() -> > bpf_object__load_skeleton() -> bpf_object_load() -> bpf_object__loadxattr() > > We would have to add kern_version to 'bpf_object_skeleton' struct, to be > passed to 'bpf_object__load_skeleton()' to have it passed on. > > I'll let Andrii to see what he prefers. See my reply to John. What he asked for already exists. Having a test would be nice, but selftests/bpf don't have an infrastructure to even perform this test, so I don't think it's worth it. So in summary, LGTM. I'll apply it once bpf-next is ready to accept new patches. Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > Note: > > Reason for all this (including the legacy kprobe logic, in other commit) > is to continue the > https://github.com/rafaeldtinoco/conntracker/tree/poc-cmd project, > making sure it supports 4.x kernels. Still adding bpf support to it > (identify task/pid per flow) and will replace the libnf* usage with bpf > after that. > > Thanks > -rafaeldtinoco
