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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Wed, 24 Jun 2020 12:27:17 -0700
Message-ID: <CAEf4BzakcsdDcoeUN4uwigFti6iJrAu2Ge3EPfJm1cHyUq5W=Q@mail.gmail.com>
Subject: Re: tools/bpf: build failed with defconfig(x86_64) on v5.6 and v5.7
To:     Li Xinhai <lixinhai.lxh@gmail.com>
Cc:     bpf <bpf@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Tue, Jun 23, 2020 at 11:46 PM Li Xinhai <lixinhai.lxh@gmail.com> wrote:
>
> - information of machine
> Linux localhost.localdomain 4.18.0-193.6.3.el8_2.x86_64 #1 SMP Wed Jun 10=
 11:09:32 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
>
> - configurations
> make defconfig
> make kvmconfig
>
> - failed logs on v5.6
> ```
>   LINK     /mnt/build/1_build/05_build_v5.6/bpf/bpftool//libbpf/libbpf.a
>   LINK     /mnt/build/1_build/05_build_v5.6/bpf/bpftool/bpftool
>   DESCEND  runqslower
>   GEN      /mnt/build/0_code/0_linux/linux/tools/bpf/runqslower/.output/b=
pf_helper_defs.h
> make[4]: *** No rule to make target '/mnt/build/0_code/0_linux/linux/tool=
s/include/linux/build_bug.h', needed by '/mnt/build/0_code/0_linux/linux/to=
ols/bpf/runqslower/.output/staticobjs/libbpf.o'.  Stop.
> make[3]: *** [Makefile:183: /mnt/build/0_code/0_linux/linux/tools/bpf/run=
qslower/.output/staticobjs/libbpf-in.o] Error 2
> make[2]: *** [Makefile:79: .output/libbpf.a] Error 2
> make[1]: *** [Makefile:119: runqslower] Error 2
> make: *** [Makefile:68: bpf] Error 2
> ```
>
> - failed logs on v5.7
> ```
> In file included from /mnt/build/0_code/0_linux/linux/tools/include/linux=
/build_bug.h:5,
>                  from /mnt/build/0_code/0_linux/linux/tools/include/linux=
/kernel.h:8,
>                  from /mnt/build/0_code/0_linux/linux/kernel/bpf/disasm.h=
:10,
>                  from /mnt/build/0_code/0_linux/linux/kernel/bpf/disasm.c=
:8:
> /mnt/build/0_code/0_linux/linux/kernel/bpf/disasm.c: In function =E2=80=
=98__func_get_name=E2=80=99:
> /mnt/build/0_code/0_linux/linux/tools/include/linux/compiler.h:37:38: war=
ning: nested extern declaration of =E2=80=98__compiletime_assert_0=E2=80=99=
 [-Wnested-externs]
>   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>                                       ^~~~~~~~~~~~~~~~~~~~~
> /mnt/build/0_code/0_linux/linux/tools/include/linux/compiler.h:16:15: not=
e: in definition of macro =E2=80=98__compiletime_assert=E2=80=99
>    extern void prefix ## suffix(void) __compiletime_error(msg); \
>                ^~~~~~
> /mnt/build/0_code/0_linux/linux/tools/include/linux/compiler.h:37:2: note=
: in expansion of macro =E2=80=98_compiletime_assert=E2=80=99
>   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>   ^~~~~~~~~~~~~~~~~~~
> /mnt/build/0_code/0_linux/linux/tools/include/linux/build_bug.h:39:37: no=
te: in expansion of macro =E2=80=98compiletime_assert=E2=80=99
>  #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>                                      ^~~~~~~~~~~~~~~~~~
> /mnt/build/0_code/0_linux/linux/tools/include/linux/build_bug.h:50:2: not=
e: in expansion of macro =E2=80=98BUILD_BUG_ON_MSG=E2=80=99
>   BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
>   ^~~~~~~~~~~~~~~~
> /mnt/build/0_code/0_linux/linux/kernel/bpf/disasm.c:20:2: note: in expans=
ion of macro =E2=80=98BUILD_BUG_ON=E2=80=99
>   BUILD_BUG_ON(ARRAY_SIZE(func_id_str) !=3D __BPF_FUNC_MAX_ID);
>   ^~~~~~~~~~~~
> ```
>

This one I've seen and I have no idea why this is happening (suddenly)
and how to fix that.

> and
> ```
>   LINK     /mnt/build/0_code/0_linux/linux/tools/bpf/runqslower/.output/l=
ibbpf.a
>   GEN      vmlinux.h
>   BPF      runqslower.bpf.o
> In file included from runqslower.bpf.c:3:
> .output/vmlinux.h:5:15: error: attribute 'preserve_access_index' is not s=
upported by '#pragma clang attribute'
> #pragma clang attribute push (__attribute__((preserve_access_index)), app=
ly_to =3D record)
>               ^
> .output/vmlinux.h:98607:15: error: '#pragma clang attribute pop' with no =
matching '#pragma clang attribute push'
> #pragma clang attribute pop
>               ^
> 2 errors generated.
> make[2]: *** [Makefile:57: .output/runqslower.bpf.o] Error 1
> make[1]: *** [Makefile:119: runqslower] Error 2
> make: *** [Makefile:68: bpf] Error 2
> ```
>

This just means you don't have recent-enough Clang on your system. You
need Clang 10 at least.


> On this same machine and with same configuration, I've tried v5.4 and v5.=
5, no failures.
>
>