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perf tools: Provide backward compatibility with previous perf.data version 

We have merged the trace.info file into perf.data by adding one
section in the perf headers. This makes it incompatible with
previous version: the new perf tools can't read the older
perf.data.

To support the previous format, we check the headers size. If they
have the same size than in the previous format, then ignore the
trace info section that doesn't exist.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1255032449-12022-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2009-10-08 22:07:29 +02:00 committed by Ingo Molnar
parent 97ea1a7fa6
commit 26dd2cb074
1 changed files with 7 additions and 1 deletions
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8
tools/perf/util/header.c
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@ -287,10 +287,16 @@ struct perf_header *perf_header__read(int fd)
do_read(fd, &f_header, sizeof(f_header));
if (f_header.magic != PERF_MAGIC ||
f_header.size != sizeof(f_header) ||
f_header.attr_size != sizeof(f_attr))
die("incompatible file format");
if (f_header.size != sizeof(f_header)) {
/* Support the previous format */
if (f_header.size == offsetof(typeof(f_header), trace_info))
f_header.trace_info.size = 0;
else
die("incompatible file format");
}
nr_attrs = f_header.attrs.size / sizeof(f_attr);
lseek(fd, f_header.attrs.offset, SEEK_SET);