BPF elf examples

BPF elf examples

[Stephen Hemminger]

While looking in more detail at BPF use of VLA, went down a rabbit hole
because there are no tests and no examples of loading a BPF program using
the elf_load API's in BPF.

Tried using AI to generate tests, and as usual it sort of worked but the
example code generated won't load or work. Is there anywhere to find working
DPDK examples of using BPF load?

RE: BPF elf examples

[Konstantin Ananyev]

> While looking in more detail at BPF use of VLA, went down a rabbit hole
> because there are no tests and no examples of loading a BPF program using
> the elf_load API's in BPF.
> 
> Tried using AI to generate tests, and as usual it sort of worked but the
> example code generated won't load or work. Is there anywhere to find working
> DPDK examples of using BPF load? 

app/test-pmd/bpf_cmd.c calls rte_bpf_eth_rx_elf_load/ rte_bpf_eth_tx_elf_load,
which in turn calls rte_bpf_elf_load().
Though it is a good point, will think can we add a UT for it too.

RE: BPF elf examples

[Marat Khalili]

> -----Original Message-----
> Tried using AI to generate tests, and as usual it sort of worked but the
> example code generated won't load or work. Is there anywhere to find working
> DPDK examples of using BPF load?

Hello! I'm sitting on some patches adding a framework for generating BPF ELF 
files using libelf and some basic unit tests based on it. Hopefully I'll be 
able to upstream it within the next couple of months.

Generating ELF files is probably beyond the reach of current AI, but once the 
framework is there perhaps it could be used to add test cases, would be 
interesting to try...

Re: BPF elf examples

[Stephen Hemminger]

On Tue, 21 Oct 2025 11:42:25 +0000
Marat Khalili <marat.khalili@huawei.com> wrote:

> > -----Original Message-----
> > Tried using AI to generate tests, and as usual it sort of worked but the
> > example code generated won't load or work. Is there anywhere to find working
> > DPDK examples of using BPF load?  
> 
> Hello! I'm sitting on some patches adding a framework for generating BPF ELF 
> files using libelf and some basic unit tests based on it. Hopefully I'll be 
> able to upstream it within the next couple of months.
> 
> Generating ELF files is probably beyond the reach of current AI, but once the 
> framework is there perhaps it could be used to add test cases, would be 
> interesting to try...

I have sample programs now (thanks AI). But building them in meson is messy.
And integrating standalone files in UT is brittle.
Perhaps using bpftool like tap driver does to generate a header file (.h) and
then have UT write a /tmp file to load.