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From: Dave Marchevsky <davemarchevsky@fb.com>
To: Yonghong Song <yhs@fb.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	kernel-team@fb.com
Subject: Re: [PATCH bpf-next 06/12] selftests/bpf: Fix selftests failure
Date: Sun, 8 May 2022 22:21:24 -0400	[thread overview]
Message-ID: <d99ef512-5c1a-0763-c780-d7f37087c23c@fb.com> (raw)
In-Reply-To: <20220501190033.2579182-1-yhs@fb.com>

On 5/1/22 3:00 PM, Yonghong Song wrote:   
> The kflag is supported now for BTF_KIND_ENUM.
> So remove the test which tests verifier failure
> due to existence of kflag.
> 
> With enum64 support in kernel and libbpf,
> selftest btf_dump/btf_dump failed with
> no-enum64 support llvm for the following
> enum definition:
>  enum e2 {
>         C = 100,
>         D = 4294967295,
>         E = 0,
>  };
> 
> With the no-enum64 support llvm, the signedness is
> 'signed' by default, and D (4294967295 = 0xffffffff)
> will print as -1. With enum64 support llvm, the signedness
> is 'unsigned' and the value of D will print as 4294967295.

To confirm my understanding, this signedness-by-default change is for _printing
btf in c format only_ and doesn't correspond to any difference in interpretation
, since all BTF enums before addition of new kflag were assumed to be signed,
and new kflag's default value is signed as well.

> To support both old and new compilers, this patch
> changed the value to 268435455 = 0xfffffff which works
> with both enum64 or non-enum64 support llvm.
> 
> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---

Aside from the general question, for changes in this patch:

Acked-by: Dave Marchevsky <davemarchevsky@fb.com>

  reply	other threads:[~2022-05-09  2:22 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-01 19:00 [PATCH bpf-next 00/12] bpf: Add 64bit enum value support Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 01/12] bpf: Add btf enum64 support Yonghong Song
2022-05-09  0:33   ` Dave Marchevsky
2022-05-09 22:29   ` Andrii Nakryiko
2022-05-10 22:06     ` Yonghong Song
2022-05-10 23:18       ` Andrii Nakryiko
2022-05-11  0:17         ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 02/12] libbpf: Permit 64bit relocation value Yonghong Song
2022-05-09  1:06   ` Dave Marchevsky
2022-05-10 19:35     ` Yonghong Song
2022-05-09 22:37   ` Andrii Nakryiko
2022-05-10 22:14     ` Yonghong Song
2022-05-10 23:19       ` Andrii Nakryiko
2022-05-01 19:00 ` [PATCH bpf-next 03/12] libbpf: Fix an error in 64bit relocation value computation Yonghong Song
2022-05-09  0:55   ` Dave Marchevsky
2022-05-09  0:56     ` Dave Marchevsky
2022-05-09 22:37   ` Andrii Nakryiko
2022-05-10 22:11     ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 04/12] libbpf: Add btf enum64 support Yonghong Song
2022-05-03 17:22   ` kernel test robot
2022-05-05 22:44     ` Yonghong Song
2022-05-05 22:44       ` Yonghong Song
2022-05-09 23:25   ` Andrii Nakryiko
2022-05-10 22:40     ` Yonghong Song
2022-05-10 23:02       ` Yonghong Song
2022-05-10 23:40         ` Andrii Nakryiko
2022-05-10 23:38       ` Andrii Nakryiko
2022-05-11  0:39         ` Yonghong Song
2022-05-11 17:43           ` Andrii Nakryiko
2022-05-11 18:56             ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 05/12] bpftool: " Yonghong Song
2022-05-09 23:31   ` Andrii Nakryiko
2022-05-10 22:43     ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 06/12] selftests/bpf: Fix selftests failure Yonghong Song
2022-05-09  2:21   ` Dave Marchevsky [this message]
2022-05-10 19:40     ` Yonghong Song
2022-05-09 23:34   ` Andrii Nakryiko
2022-05-10 22:44     ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 07/12] selftests/bpf: Test new libbpf enum32/enum64 API functions Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 08/12] selftests/bpf: Add BTF_KIND_ENUM64 unit tests Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 09/12] selftests/bpf: Test BTF_KIND_ENUM64 for deduplication Yonghong Song
2022-05-09 23:37   ` Andrii Nakryiko
2022-05-10 22:44     ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 10/12] selftests/bpf: add a test for enum64 value relocation Yonghong Song
2022-05-09 23:38   ` Andrii Nakryiko
2022-05-10 22:45     ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 11/12] selftests/bpf: Clarify llvm dependency with possible selftest failures Yonghong Song
2022-05-01 19:01 ` [PATCH bpf-next 12/12] docs/bpf: Update documentation for BTF_KIND_ENUM64 support Yonghong Song

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