Re: next: zip.c:35:8: error: packed attribute causes inefficient alignment for 'magic' [-Werror=attributes]

[Andrii Nakryiko]

On Mon, Mar 13, 2023 at 11:38 PM Naresh Kamboju
<naresh.kamboju@xxxxxxxxxx> wrote:
>
> perf builds failing from Linux next-20230307..next-20230314 but pass on
> Linux mainline v6.3-rc2.
>
> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

Thanks for the report, but I'm not sure what's wrong here. We added
__attribute__((packed)) attribute intentionally and want to keep it
this way. It seems like perf itself is using packed structs (e.g.,
struct debug_line_header in util/genelf_debug.c), so I'm wondering why
that code doesn't cause any problems.

Any hints from perf folks?


>
> Build log:
> ---
> libbpf/staticobjs/zip.o
> zip.c:35:8: error: packed attribute causes inefficient alignment for
> 'magic' [-Werror=attributes]
>    35 |  __u32 magic;
>       |        ^~~~~
> zip.c:40:8: error: packed attribute causes inefficient alignment for
> 'this_disk' [-Werror=attributes]
>    40 |  __u16 this_disk;
>       |        ^~~~~~~~~
> zip.c:45:8: error: packed attribute causes inefficient alignment for
> 'cd_disk' [-Werror=attributes]
>    45 |  __u16 cd_disk;
>       |        ^~~~~~~
> zip.c:50:8: error: packed attribute causes inefficient alignment for
> 'cd_records' [-Werror=attributes]
>    50 |  __u16 cd_records;
>       |        ^~~~~~~~~~
> zip.c:55:8: error: packed attribute causes inefficient alignment for
> 'cd_records_total' [-Werror=attributes]
>    55 |  __u16 cd_records_total;
>       |        ^~~~~~~~~~~~~~~~
> zip.c:58:8: error: packed attribute causes inefficient alignment for
> 'cd_size' [-Werror=attributes]
>    58 |  __u32 cd_size;
>       |        ^~~~~~~
> zip.c:63:8: error: packed attribute causes inefficient alignment for
> 'cd_offset' [-Werror=attributes]
>    63 |  __u32 cd_offset;
>       |        ^~~~~~~~~
> zip.c:66:8: error: packed attribute causes inefficient alignment for
> 'comment_length' [-Werror=attributes]
>    66 |  __u16 comment_length;
>       |        ^~~~~~~~~~~~~~
> zip.c:79:8: error: packed attribute causes inefficient alignment for
> 'magic' [-Werror=attributes]
>    79 |  __u32 magic;
>       |        ^~~~~
> zip.c:80:8: error: packed attribute causes inefficient alignment for
> 'version' [-Werror=attributes]
>    80 |  __u16 version;
>       |        ^~~~~~~
> zip.c:82:8: error: packed attribute causes inefficient alignment for
> 'min_version' [-Werror=attributes]
>    82 |  __u16 min_version;
>       |        ^~~~~~~~~~~
> zip.c:83:8: error: packed attribute causes inefficient alignment for
> 'flags' [-Werror=attributes]
>    83 |  __u16 flags;
>       |        ^~~~~
> zip.c:84:8: error: packed attribute causes inefficient alignment for
> 'compression' [-Werror=attributes]
>    84 |  __u16 compression;
>       |        ^~~~~~~~~~~
> zip.c:85:8: error: packed attribute causes inefficient alignment for
> 'last_modified_time' [-Werror=attributes]
>    85 |  __u16 last_modified_time;
>       |        ^~~~~~~~~~~~~~~~~~
> zip.c:86:8: error: packed attribute causes inefficient alignment for
> 'last_modified_date' [-Werror=attributes]
>    86 |  __u16 last_modified_date;
>       |        ^~~~~~~~~~~~~~~~~~
> zip.c:87:8: error: packed attribute causes inefficient alignment for
> 'crc' [-Werror=attributes]
>    87 |  __u32 crc;
>       |        ^~~
> zip.c:88:8: error: packed attribute causes inefficient alignment for
> 'compressed_size' [-Werror=attributes]
>    88 |  __u32 compressed_size;
>       |        ^~~~~~~~~~~~~~~
> zip.c:89:8: error: packed attribute causes inefficient alignment for
> 'uncompressed_size' [-Werror=attributes]
>    89 |  __u32 uncompressed_size;
>       |        ^~~~~~~~~~~~~~~~~
> zip.c:90:8: error: packed attribute causes inefficient alignment for
> 'file_name_length' [-Werror=attributes]
>    90 |  __u16 file_name_length;
>       |        ^~~~~~~~~~~~~~~~
> zip.c:91:8: error: packed attribute causes inefficient alignment for
> 'extra_field_length' [-Werror=attributes]
>    91 |  __u16 extra_field_length;
>       |        ^~~~~~~~~~~~~~~~~~
> zip.c:92:8: error: packed attribute causes inefficient alignment for
> 'file_comment_length' [-Werror=attributes]
>    92 |  __u16 file_comment_length;
>       |        ^~~~~~~~~~~~~~~~~~~
> zip.c:94:8: error: packed attribute causes inefficient alignment for
> 'disk' [-Werror=attributes]
>    94 |  __u16 disk;
>       |        ^~~~
> zip.c:95:8: error: packed attribute causes inefficient alignment for
> 'internal_attributes' [-Werror=attributes]
>    95 |  __u16 internal_attributes;
>       |        ^~~~~~~~~~~~~~~~~~~
> zip.c:108:8: error: packed attribute causes inefficient alignment for
> 'magic' [-Werror=attributes]
>   108 |  __u32 magic;
>       |        ^~~~~
> zip.c:110:8: error: packed attribute causes inefficient alignment for
> 'min_version' [-Werror=attributes]
>   110 |  __u16 min_version;
>       |        ^~~~~~~~~~~
> zip.c:111:8: error: packed attribute causes inefficient alignment for
> 'flags' [-Werror=attributes]
>   111 |  __u16 flags;
>       |        ^~~~~
> zip.c:112:8: error: packed attribute causes inefficient alignment for
> 'compression' [-Werror=attributes]
>   112 |  __u16 compression;
>       |        ^~~~~~~~~~~
> zip.c:113:8: error: packed attribute causes inefficient alignment for
> 'last_modified_time' [-Werror=attributes]
>   113 |  __u16 last_modified_time;
>       |        ^~~~~~~~~~~~~~~~~~
> zip.c:114:8: error: packed attribute causes inefficient alignment for
> 'last_modified_date' [-Werror=attributes]
>   114 |  __u16 last_modified_date;
>       |        ^~~~~~~~~~~~~~~~~~
> zip.c:118:8: error: packed attribute causes inefficient alignment for
> 'file_name_length' [-Werror=attributes]
>   118 |  __u16 file_name_length;
>       |        ^~~~~~~~~~~~~~~~
> zip.c:119:8: error: packed attribute causes inefficient alignment for
> 'extra_field_length' [-Werror=attributes]
>   119 |  __u16 extra_field_length;
>       |        ^~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
>
> Build links,
> https://storage.tuxsuite.com/public/linaro/lkft/builds/2MfXEyvgh4ba9y3rkt6KPf6sUMR/
>
>
> History link,
> https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230314/testrun/15564056/suite/build/test/gcc-10-lkftconfig-perf/history/
>
>
> --
> Linaro LKFT
> https://lkft.linaro.org