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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Tue, 31 Mar 2020 12:52:34 -0700
Message-ID: <CAEf4BzaAZ5Qop0z8r+SBNQyPtt0+EpKy9Q0EkcSDkTZw54Bnaw@mail.gmail.com>
Subject: Re: [PATCH] kbuild: disable DEBUG_INFO_SPLIT when BTF is on
To:     Slava Bacherikov <slava@bacher09.org>
Cc:     Masahiro Yamada <yamada.masahiro@socionext.com>,
        Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>
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On Tue, Mar 31, 2020 at 12:45 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Tue, Mar 31, 2020 at 9:57 AM Slava Bacherikov <slava@bacher09.org> wrote:
> >
> > Currently turning on DEBUG_INFO_SPLIT when DEBUG_INFO_BTF is also
> > enabled will produce invalid btf file, since gen_btf function in
> > link-vmlinux.sh script doesn't handle *.dwo files.
> >
> > Signed-off-by: Slava Bacherikov <slava@bacher09.org>
> > ---
> >  lib/Kconfig.debug | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index f61d834e02fe..a9429ef5eec8 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -223,6 +223,7 @@ config DEBUG_INFO_DWARF4
> >  config DEBUG_INFO_BTF
> >         bool "Generate BTF typeinfo"
> >         depends on DEBUG_INFO
> > +       depends on !DEBUG_INFO_SPLIT
>
> Thanks for following up! This looks good, but I think there are more
> DWARF-related configs that should be banned. See [0] and [1]. If you
> don't mind, let's use your patch to disable all of them in one go. So
> can you please update and disable DEBUG_INFO_REDUCED and
> GCC_PLUGIN_RANDSTRUCT? Thanks!
>
>   [0] https://lore.kernel.org/bpf/202003311110.2B08091E@keescook
>   [1] https://lore.kernel.org/bpf/a2b1a025-6a70-c3a5-fc19-155f0266946a@fb.com
>

I guess at this point it should go against bpf tree, so please update
header to [PATCH v2 bpf]. Please also add Reported-by and Fixes tag:

Reported-by: Jann Horn <jannh@google.com>
Reported-by: Liu Yiding <liuyd.fnst@cn.fujitsu.com>
Fixes: e83b9f55448a ("kbuild: add ability to generate BTF type info
for vmlinux")

Thanks!

>
> >         help
> >           Generate deduplicated BTF type information from DWARF debug info.
> >           Turning this on expects presence of pahole tool, which will convert
> > --
> > 2.24.1
> >