On Thu, 4 Apr 2024 01:49:56 +0100 Luca Boccassi <bl...@debian.org> wrote:
> On Thu, 4 Apr 2024 at 00:41, Stephen Hemminger > <step...@networkplumber.org> wrote: > > > > On Wed, 3 Apr 2024 22:19:20 +0100 > > Luca Boccassi <bl...@debian.org> wrote: > > > > > On Wed, 3 Apr 2024 at 16:55, Stephen Hemminger > > > <step...@networkplumber.org> wrote: > > > > > > > > On Wed, 03 Apr 2024 12:50:35 +0100 > > > > Luca Boccassi <bl...@debian.org> wrote: > > > > > > > > > Using bpftool to generate the header at build time is a bit icky, > > > > > because it will look at sysfs on the build system, which is from the > > > > > running kernel. But a build system's kernel might be some ancient LTS, > > > > > and even be a completely different kconfig/build/distro from the > > > > > actual > > > > > runtime one. > > > > > > > > One other option would be to ship a pre-built skeleton file. > > > > Which is what the method the old code did. > > > > But that creates an implied dependency on the developers machine build > > > > environment. > > > > > > That's what the distro-provided vmlinux.h should help with - by > > > #include'ing that, it should be possible to build a co-re bpf program, > > > no other artifacts needed. You can try it out locally by generating it > > > from the local running kernel on your dev machine: > > > > > > bpftool btf dump file /sys/kernel/btf/vmlinux format c > vmlinux.h > > > > Not all distros are providing vmlinux.h. > > And some like Ubuntu haven't figured out how to package bpftool and libbpf > > correctly. > > Yes and for those the usual pattern is a fallback to generate at build > time, if no pre-prepared vmlinux.h is configured Looks like vmlinux.h is not setup to handle tc programs. If vmlinux.h is included, it supersedes other kernel headers (ok). But is missing some other things like IPv6 options, ether types, and TC actions. To use it requires copy pasting from other headers to fill in the missing pieces. Thats a mess. This little program only refers to skb and the fields that are problematic are protocol, mark, and queue_mapping.
