Re: [PATCH net-next v2 3/3] tools: bpftool: add documentation

[David Ahern <dsahern@gmail.com>]

On 10/3/17 9:01 AM, Daniel Borkmann wrote:
> On 10/03/2017 05:39 PM, David Ahern wrote:
>> On 10/2/17 9:29 PM, Alexei Starovoitov wrote:
>>> On Mon, Oct 02, 2017 at 06:35:09PM -0700, Jakub Kicinski wrote:
>>>>> will pretty print them as verifier output as well?
>>>>
>>>> We tried to use LLVM as a library for this but the interface is
>>>> painfully unstable and it's a heavy dependency.  The current thinking
>>>> is to try to put the instruction printing code in some higher level
>>>> library, but I would rather leave that as a follow up.
>>>
>>> follow up, of course.
>>> Not depending on llvm is must have for this tool.
>>> I think we need tiny and simple tools first.
>>> Since you're using gpl+bsd license for this tool I think
>>> it would be fine to copy-paste verifier's pretty print code into it.
>>
>> I have done that including integrating it into bpf-tool.
> 
> Great, to avoid letting the pretty print code become stale,
> could the printer be ripped out of the verifier into its own
> file or header under kernel/bpf/ such that it can be used from
> kernel but also integrated from bpftool compilation? There's
> likely not much kernel specifics in there anyway, wdyt?

The pretty print code I have is based on the verifier code from
February. At this point I forget all of the changes I made to it in the
past 7 months.

I agree that it would be best to try to pull the verifier code into a
separate file for easier re-use and keeping the tool up to date.