04/07/2018 21:47, Ferruh Yigit: > On 6/12/2018 3:02 PM, Ophir Munk wrote: > > Please note that other than cloning iproute2 we also need to install clang > > and llvm tools versions 3.7 and upper. > > Not sure there are clang and llvm packages of the required versions for the > > common distributions. > > I compiled the tools source code and installed them manually. > > Hi Keith, Thomas, > > What do you suggest on this patch? > > The "tap_bpf_program.c" is already withing the tap pmd this patch improves the > doc about how to compile it, although it may not be so user friendly as Keith > pointed, I believe better to get doc improvement here. > > And there is a code update "+#include "bpf_api.h", which includes a iproute2 > header, I am not sure about this one and how to manage this dependency.
If you feel it needs some improvement, we can postpone it for 18.11. The most important is to have a patch to reference when somebody asks. It can be improved and merged later, no pressure. > >> -----Original Message----- > >> From: Wiles, Keith [mailto:keith.wi...@intel.com] > >> > >>> On Jun 12, 2018, at 8:44 AM, Thomas Monjalon <tho...@monjalon.net> > >> wrote: > >>> > >>> 12/06/2018 15:33, Wiles, Keith: > >>>> > >>>>> On Jun 12, 2018, at 7:58 AM, Thomas Monjalon > >> <tho...@monjalon.net> wrote: > >>>>> > >>>>> 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? > >>>> > >>>> Well the dependence of iproute2 is really no different then requiring say > >> libnuma, they just have to pull the code first to type the ‘make > >> bpf_program’ > >> right? > >>> > >>> The iproute2 dependency is different because it is not a library. > >>> The .h file is never packaged. > >>> So we need to download the sources and set -I to this directory. > >> > >> To eliminate the -I problem the clone could be done inside the tap > >> directory > >> and -I ./iproute2/include used, right? > >> The make target could even clone the code into the tap directory, which > >> means we can solve these problems you are pointing out. > >> > >> Go ahead and do what you want here, but making it harder for the developer > >> should not be our normally mode of operation. > >> > >>> > >>> > >>>> If that is the case then a make target make sense to me. If iproute2 is > >>>> not > >> found then an error, right? > >>> > >>> > >>>>>>> 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. > >>>> > >>>> Please change the doc to reflect the tool is not upstreamed yet and the > >> developer needs to figure out how to extract the data from the binary. > >>>> > >>>> I used objdump -j l3_l4 -s tap_bpf_program.o and got a hex dump of > >>>> the l3_l4 section > >>>> > >>>> 0000 bf160000 00000000 61681000 00000000 <Ascii characters> ... > >>>> > >>>> Someone schooled in the art of Python coding should be able to > >>>> convert that output to a ‘C’ data array. :-) > >>>> > >>>>> > >>>>>>> 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. > >>>> > >>>> Regards, > >>>> Keith > >> > >> Regards, > >> Keith > > > >
