Re: FYI: CI regression on big-endian arch (s390) after recent pahole changes

[Eduard Zingerman <eddyz87@gmail.com>]

On Thu, 2024-08-29 at 18:27 -0700, Tony Ambardar wrote:


> Thanks for looking at this. I ran into the CI failure while using s390x
> to test a series adding libbpf bi-endian support. Since I'm deep into
> endianness issues right now, I thought to try the fix you suggested just
> to make some progress but noticed the CI failure has disappeared.[0]

Hi Tony,

There is no fix yet, sorry :)
I think that something like below should do the trick:

--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -5394,6 +5394,7 @@ int btf__distill_base(const struct btf *src_btf, struct btf **new_base_btf,
        new_base = btf__new_empty();
        if (!new_base)
                return libbpf_err(-ENOMEM);
+       btf__set_endianness(new_base, btf__endianness(src_btf));
        dist.id_map = calloc(n, sizeof(*dist.id_map));
        if (!dist.id_map) {
                err = -ENOMEM;

as far as I understand btf__raw_data() should do all conversions after this.
But I have not tested it yet and would be AFK for a few hours.

> Did something get fixed already? I can't seem to find the change.

pahole version w/o support for distilled base was pinned on CI:
https://github.com/kernel-patches/vmtest/pull/285/commits/d3eff26fc978ca8fb3bce3f93421f7425aef0f55


Thanks,
Eduard