From 26dd2cb074d9dc41c9e3cddd7bf175fd0a41febc Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 8 Oct 2009 22:07:29 +0200 Subject: [PATCH] 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 Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Mike Galbraith Cc: Paul Mackerras LKML-Reference: <1255032449-12022-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- tools/perf/util/header.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 212fade7ee7..9aae360c0f2 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -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);