Re: [PATCH 6/7] perf, tool: Fix endianity trick for adds_features bitmask

[David Ahern <dsahern@gmail.com>]

On 5/16/12 12:59 AM, Jiri Olsa wrote:
> Addons bitmask is stored as array of unsigned long values. The size
> of the unsigned long is same as pointer size for architecture, so it
> could differ for each architecture.
>
> To handle the endianity for adds_features bitmask, we first swap the
> bitmaks as u64 values and check for HEADER_HOSTNAME bit. If not set we
> want to unswap the u64 values and swap the adds_features as u32 values.
>
> This is currently buggy, since we swap just first 32bits of each u64
> value. Adding swap of the next 32 bits as well.  Also adding&  using
> BITS_TO_U64 instead of BITS_TO_LONGS as counter max due to the different
> size of unsigned longs per architecture.
>
> Note, running following to test perf endianity handling:
> test 1)
>    - origin system:
>      # perf record -a -- sleep 10 (any perf record will do)
>      # perf report>  report.origin
>      # perf archive perf.data
>
>    - copy the perf.data, report.origin and perf.data.tar.bz2
>      to a target system and run:
>      # tar xjvf perf.data.tar.bz2 -C ~/.debug
>      # perf report>  report.target
>      # diff -u report.origin report.target
>
>    - the diff should produce no output
>      (besides some white space stuff and possibly different
>       date/TZ output)
>
> test 2)
>    - origin system:
>      # perf record -ag -fo /tmp/perf.data -- sleep 1
>    - mount origin system root to the target system on /mnt/origin
>    - target system:
>      # perf script --symfs /mnt/origin -I -i /mnt/origin/tmp/perf.data \
>       --kallsyms /mnt/origin/proc/kallsyms
>    - complete perf.data header is displayed
>
> Signed-off-by: Jiri Olsa<jolsa@redhat.com>

32-bit ppc reading 64-bit x86 still does not work:

# ========
# captured on: Sun May 20 19:23:23 2012
# ========
#

Why not? It suggests there is still a bug in the processing of the 
adds_feature bitmap.

David