On Fri, Apr 25, 2025 at 1:25 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> writes:
>
> [...]
>
> >> $ diff -pruN ~/tmp/task_struct.ko.c ~/tmp/task_struct.vmlinux.c
> >> --- /home/ezingerman/tmp/task_struct.ko.c 2025-04-25 12:37:48.312480603 -0700
> >> +++ /home/ezingerman/tmp/task_struct.vmlinux.c 2025-04-25 12:38:03.096644654 -0700
> >> @@ -18,7 +18,6 @@ struct task_struct {
> >> int static_prio;
> >> int normal_prio;
> >> unsigned int rt_priority;
> >> - long: 0;
> >> struct sched_entity se;
> >
> > I reproed this issue with default .ko build that includes:
> > --btf_features=distilled_base
> >
> > Once I disabled it and did
> > bpftool btf dump file ./bpf_testmod.ko --base-btf .../vmlinux format c
> > the task_struct from vmlinux.h and from testmod.h became exactly the same.
> > So it sounds like the 3rd issue :)
> > bpftool dump of distilled btf needs work.
>
> Mystery upon mystery.
> Here is a continuation of the last one.
> This is raw BTF for .ko:
>
> [509] STRUCT 'task_struct' size=10496 vlen=268
> ...
> 'rt_priority' type_id=3 bits_offset=960
> ...
>
> And this is raw BTF for vmlinux:
>
> [1] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none)
> [2] CONST '(anon)' type_id=1
> [3] VOLATILE '(anon)' type_id=2
> ...
> [9] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none)
> ...
> [111] STRUCT 'task_struct' size=10496 vlen=268
> ...
> 'rt_priority' type_id=9 bits_offset=960
> ...
>
> Note type conflict 'volatile const long' vs 'unsigned int'.
> Either something is very broken or I completely messed up the build.
You didn't turn off distilled_base :)
