On Wed, 2024-02-28 at 16:02 -0800, Andrii Nakryiko wrote:
> On Wed, Feb 28, 2024 at 3:55 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> >
[...]
> > On Wed, 2024-02-28 at 15:43 -0800, Andrii Nakryiko wrote:
> > > > +SEC(".struct_ops.link")
> > >
> > > can you please also have a test where we use SEC("?.struct_ops.link")
> > > which set autoload to false by default?
> >
> > As far as I understand, that would be a new behavior, currently '?'
> > works only for programs. I'll add a separate patch to support this.
> >
>
> Yep, thanks!
So, I have a draft for v2 with support for this feature in [0].
But there is a gotcha:
libbpf: BTF loading error: -22
libbpf: -- BEGIN BTF LOAD LOG ---
...
[23] DATASEC ?.struct_ops size=8 vlen=1 Invalid name
-- END BTF LOAD LOG --
libbpf: Error loading .BTF into kernel: -22. BTF is mandatory, can't proceed.
Kernel rejects DATASEC name with '?'.
The options are:
1. Tweak kernel to allow '?' as a first char in DATASEC names;
2. Use some different name, e.g. ".struct_ops.opt";
3. Do some kind of BTF rewrite in libbpf to merge
"?.struct_ops" and ".struct_ops" DATASECs as a single DATASEC.
(1) is simple, but downside is requirement for kernel upgrade;
(2) is simple, but goes against current convention for program section names;
(3) idk, will check if that is feasible tomorrow.
[0] https://github.com/eddyz87/bpf/tree/structops-multi-version
