12/06/2018 14:36, Wiles, Keith: > > > On Jun 12, 2018, at 7:26 AM, Thomas Monjalon <tho...@monjalon.net> wrote: > > > > 11/06/2018 18:35, Wiles, Keith: > >> > >>> On Jun 11, 2018, at 11:06 AM, Ophir Munk <ophi...@mellanox.com> wrote: > >>> > >>> This commit explains how to manually compile the C source file > >>> tap_bpf_program.c into an ELF file using the clang compiler. > >>> The code in tap_bpf_program.c requires definitions found in iproute2 > >>> source code. This commit suggests cloning the iproute2 git tree and > >>> include its path in the clang command. It also adds inclusion of file > >>> bpf_api.h (required for eBPF definitions) which is located in iproute2 > >>> source tree. For more details refer to TAP documentation. > >>> This commit is related to commits [1] and [2]. > >> > >> Normally I would have suggested that eBPF be disable in the TAP driver as > >> it requires external code and programs, but that ship has sailed. > > > > The external programs are required only to generate new instructions, > > changing the behaviour of the BPF program. > > Currently, the instructions for RSS behaviour are provided. > > > >> I would like to see building the tap_bpf_program.o as a target in the > >> Makefile, this way the developer can just run the ‘make bpf_program’ > >> target and it would be simpler and less error prone.
As explained in the documentation, for now there is a dependency on iproute2 for the compilation of this BPF program. So we cannot make it as simple as a "make command". Probably that we can rework it to change the dependency. I heard there are some good BPF libraries available now? > > For this to happen, we need to improve the tools. > > In what way do we need to improve the tools and which tools are we talking > about. Building the .o file below appears to be a simple set of command > lines. I have a question in my original email about what tool. The .o file is only the an intermediate file. The next step (numbered as 5 in this patch) is to extract the section of BPF instructions to be uploaded in the kernel. This step must be done by a "tool". Ophir did it by hacking tc, but it is not upstreamed yet. There could be other ways (possibly easier) to achieve the same result. > > It is a work in progress. Contributions are welcome. > > This is a very first step to use Linux BPF with DPDK. > > If there are more interests, we should really streamline its usage > > for all parts of DPDK which runs on top of some kernel code. > > streamlining other parts of DPDK would be nice, but we are now talking about > the tap/eBPF patch.