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Date: Tue, 18 Nov 2014 14:54:48 +0900 From: Namhyung Kim <namhyung@...nel.org> To: kan.liang@...el.com Cc: acme@...nel.org, jolsa@...hat.com, a.p.zijlstra@...llo.nl, eranian@...gle.com, linux-kernel@...r.kernel.org, mingo@...hat.com, paulus@...ba.org, ak@...ux.intel.com Subject: Re: [PATCH V3 1/3] perf tools: enable LBR call stack support On Fri, 14 Nov 2014 08:44:10 -0500, kan liang wrote: > From: Kan Liang <kan.liang@...el.com> > > Currently, there are two call chain recording options, fp and dwarf. > Haswell has a new feature that utilizes the existing LBR facility to > record call chains. So it provides the third options to record call > chain. This patch enables the lbr call stack support. > > LBR call stack has some limitations. It reuses current LBR facility, so > LBR call stack and branch record can not be enabled at the same time. It > is only available for user callchain. > However, LBR call stack can work on the user app which doesn't have > frame-pointer or dwarf debug info compiled. It is a good alternative > when nothing else works. So this is only for Haswell or later, right? What if user gives it to the other CPUs - is it fail or ignore silently? I think we need to warn user about it more kindly.. Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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