On Sat, 28 Jan 2017 10:14:58 +1100 Brendan Gregg <brendan.d.gregg@...> wrote:

I did some in the bcc ref guide, but it's incomplete, and the bcc versions:
https://github.com/iovisor/bcc/blob/master/docs/reference_guide.md

Thanks! - this seem rather BCC specific syntax, and I'm looking for
documentation close for the kernel (samples/bpf/).

The best documentation I found was the man-page for the syscall bpf(2):
http://man7.org/linux/man-pages/man2/bpf.2.html

In lack of a better place, I've started documenting eBPF here:
https://prototype-kernel.readthedocs.io/en/latest/bpf/index.html

This doc is compatible with the kernels doc format, and I hope we can
push this into the kernel tree, if it turns out to be valuable?
(https://www.kernel.org/doc/html/latest/)

--Jesper

On Fri, Jan 27, 2017 at 9:54 PM, Jesper Dangaard Brouer via iovisor-dev <
iovisor-dev@...> wrote:

Hi IOvisor/eBPF people,

Do we have some documentation on eBPF maps?

Like that map types are available, and what they are useful for?

Notice, just list listing[1] the enum is not so useful:

enum bpf_map_type {
BPF_MAP_TYPE_UNSPEC,
BPF_MAP_TYPE_HASH,
BPF_MAP_TYPE_ARRAY,
BPF_MAP_TYPE_PROG_ARRAY,
BPF_MAP_TYPE_PERF_EVENT_ARRAY,
BPF_MAP_TYPE_PERCPU_HASH,
BPF_MAP_TYPE_PERCPU_ARRAY,
BPF_MAP_TYPE_STACK_TRACE,
BPF_MAP_TYPE_CGROUP_ARRAY,
BPF_MAP_TYPE_LRU_HASH,
BPF_MAP_TYPE_LRU_PERCPU_HASH,
};

[1] http://lxr.free-electrons.com/source/tools/include/uapi/
linux/bpf.h?v=4.9#L78

I also lack some documentation about how I interact with these maps...

--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer