On Sun, Aug 28, 2022 at 10:36 PM Tao Chen
<chentao.kernel@xxxxxxxxxxxxxxxxx> wrote:
>
> Hi Nakryiko, thank you for your reply. Yes, i happed to put the raw
> BTF made by myself in /boot on kernel4.19, unluckly it reported error.
> So is it possible to allow the raw BTF in /boot directly, athough we
> can set the specified btf location again to solve the problem with the
> bpf_object_open_opts interface.
>
> As you say, maybe we can remove the locations[i].raw_btf check, just
> use the btf__parse, It looks more concise.
Please don't top post, reply inline (that's kernel mail lists rules).
But yes, I think we can just use btf__parse and let libbpf figure out.
Please send a patch.
>
> 在 2022/8/26 上午4:26, Andrii Nakryiko 写道:
>
> On Wed, Aug 24, 2022 at 7:05 AM chentao.ct
> <chentao.kernel@xxxxxxxxxxxxxxxxx> wrote:
>
> Now only elf btf can be placed in the default path, raw btf should
> also can be there.
>
> It's not clear what you are trying to achieve. Do you want libbpf to
> attempt to load /boot/vmlinux-%1$s as raw BTF as well (so you can sort
> of sneak in pregenerated BTF), or what exactly?
> btf__load_vmlinux_btf() code already supports loading raw BTF, it just
> needs to be explicitly specified in locations table.
>
> So with your change locations[i].raw_btf check doesn't make sense and
> we need to clean this up.
>
> But first, let's discuss the use case, instead of your specific solution.
>
>
> Signed-off-by: chentao.ct <chentao.kernel@xxxxxxxxxxxxxxxxx>
> ---
> tools/lib/bpf/btf.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index bb1e06e..b22b5b3 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -4661,7 +4661,7 @@ struct btf *btf__load_vmlinux_btf(void)
> } locations[] = {
> /* try canonical vmlinux BTF through sysfs first */
> { "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
> - /* fall back to trying to find vmlinux ELF on disk otherwise */
> + /* fall back to trying to find vmlinux RAW/ELF on disk otherwise */
> { "/boot/vmlinux-%1$s" },
> { "/lib/modules/%1$s/vmlinux-%1$s" },
> { "/lib/modules/%1$s/build/vmlinux" },
> @@ -4686,7 +4686,7 @@ struct btf *btf__load_vmlinux_btf(void)
> if (locations[i].raw_btf)
> btf = btf__parse_raw(path);
> else
> - btf = btf__parse_elf(path, NULL);
> + btf = btf__parse(path, NULL);
> err = libbpf_get_error(btf);
> pr_debug("loading kernel BTF '%s': %d\n", path, err);
> if (err)
> --
> 2.2.1
>
