Re: [PATCH] perf data ctf: replace libbabeltrace with babeltrace2-ctf-writer

[Michael Jeanson <mjeanson@efficios.com>]

On 2026-05-20 12:13, Ian Rogers wrote:
> On Wed, May 13, 2026 at 9:06 AM Ian Rogers <irogers@google.com> wrote:
>> On Wed, May 13, 2026 at 7:14 AM Michael Jeanson <mjeanson@efficios.com> wrote:
>>> On 2026-05-12 17:54, Ian Rogers wrote:
>>>> This is cool, I'm surprised at how non-invasive the change is. I'd
>>>> done a similar thing but keeping both babeltrace 1 and 2. I'll post my
>>>> WIP in reply just as a heads up, but I have to do much more heavy
>>>> engineering.
>>>
>>> I think I can rework this to try babeltrace2-ctf-writer first and fall
>>> back on libbabeltrace1. The change is non-invasive because
>>> bt2-ctf-writer is basically just a compat API for the ctf-writer of bt1
>>> but it doesn't expose any of the new features of bt2.
>>>
>>> Your WIP patch that uses the proper libbabeltrace2 API is definitely the
>>> way to go for the long term. In the meantime would you like a v2 of this
>>> patch?
>>
>> We have a problem with the perf tool in that it carries too much
>> baggage due to its library dependencies, so I'd prefer we stick with
>> v2 support and your cleaner/simpler patch. I'm also hugely
>> appreciative of the work you've put in! I'm too busy to review my own
>> work right now, and cleaning this up ASAP offers an advantage.
> ...
>>
>> * We support libbfd although libbfd is GPLv3 and license incompatible
>> with perf, which is mainly GPLv2. We carry around libunwind support
>> but that project appears unmaintained. We have LLVM support but the
>> LLVM dependency is huge in terms of size and dependencies it brings
>> in, so people avoid building with it, etc.
> 
> What's the plan here? I'd prefer to carry the v1 patch, ie let's lose
> libbabeltrace (version 1) as a dependency.

I think I misunderstood you, I thought you wanted to keep the bt1 
support as a fallback. I'm fine with either version of the patch being 
merged.

I can send an updated version of the v1 patch addressing your review 
comments.

Cheers,

Michael