> On Jul 4, 2018, at 3:11 PM, Thomas Monjalon <tho...@monjalon.net> wrote: > > 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.
I agree. > > >>>> -----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 Regards, Keith
