linux-kernel - Re: [PATCH v3 1/7] perf tools: Set vdso name to vdso[64,32] depending on platform

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Date:	Fri, 13 May 2016 16:53:13 +0800
From:	Hekuang <hekuang@...wei.com>
To:	Adrian Hunter <adrian.hunter@...el.com>, <peterz@...radead.org>,
	<mingo@...hat.com>, <acme@...nel.org>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
	<wangnan0@...wei.com>, <jpoimboe@...hat.com>, <ak@...ux.intel.com>,
	<eranian@...gle.com>, <namhyung@...nel.org>,
	<sukadev@...ux.vnet.ibm.com>, <masami.hiramatsu.pt@...achi.com>,
	<tumanova@...ux.vnet.ibm.com>, <kan.liang@...el.com>,
	<penberg@...nel.org>, <dsahern@...il.com>
CC:	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/7] perf tools: Set vdso name to vdso[64,32] depending
 on platform



在 2016/5/12 18:06, Adrian Hunter 写道:
> On 12/05/16 11:43, He Kuang wrote:
>> This is a preparation for cross-platform vdso lookup.
>>
>> There is a naming confusion about vdso name, vdso buildid generated by
>> a 32-bit machine stores it with the name 'vdso', but when processing
>> buildid on a 64-bit machine with the same 'perf.data', perf will
>> search for vdso named as 'vdso32' and get failed.
>>
>> This patch uses different names when storing the buildid, i.e. vdso64
>> for 64-bit machine and vdso32 for 32-bit machine, and eliminates this
>> naming confusion.
> That looks like it will break existing perf.data files because they will
> have a different name recorded in the buildid section.
>
> Also it doesn't look like it would work the other way around i.e. recording
> on a 64-bit machine and processing on a 32-bit machine.

Yes, please have a look at the new patch.

Thanks
>> Signed-off-by: He Kuang <hekuang@...wei.com>
>> ---
>>   tools/perf/util/vdso.h | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/util/vdso.h b/tools/perf/util/vdso.h
>> index cdc4fab..45e9ef4 100644
>> --- a/tools/perf/util/vdso.h
>> +++ b/tools/perf/util/vdso.h
>> @@ -4,10 +4,15 @@
>>   #include <linux/types.h>
>>   #include <string.h>
>>   #include <stdbool.h>
>> +#include "util.h"
>>   
>>   #define VDSO__MAP_NAME "[vdso]"
>>   
>> -#define DSO__NAME_VDSO    "[vdso]"
>> +#if BITS_PER_LONG == 64
>> +#define DSO__NAME_VDSO    "[vdso64]"
>> +#else
>> +#define DSO__NAME_VDSO    "[vdso32]"
>> +#endif
>>   #define DSO__NAME_VDSO32  "[vdso32]"
>>   #define DSO__NAME_VDSOX32 "[vdsox32]"
>>   
>>
>