linux-kernel - Re: [PATCH v5 3/5] perf callchain: Add support for cross-platform unwind

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Date:	Fri, 27 May 2016 16:02:59 +0800
From:	Hekuang <hekuang@...wei.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	<peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<alexander.shishkin@...ux.intel.com>, <wangnan0@...wei.com>,
	<jpoimboe@...hat.com>, <ak@...ux.intel.com>, <eranian@...gle.com>,
	<namhyung@...nel.org>, <adrian.hunter@...el.com>,
	<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>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 3/5] perf callchain: Add support for cross-platform
 unwind



在 2016/5/27 15:38, Jiri Olsa 写道:
> On Fri, May 27, 2016 at 03:13:04PM +0800, Hekuang wrote:
>
> SNIP
>
>>>     - I understand we need to compile 3 objects from unwind-libunwind.c,
>>>       how about we create 3 files like:
>>>
>>>       util/unwind-libunwind-local.c
>>>       util/unwind-libunwind-x86_32.c
>>>       util/unwind-libunwind-arm64.c
>>>
>>>       which would setup all necessary defines and include unwind-libunwind.c like:
>>>
>>>       ---
>>>       /* comments explaining every define ;-) */
>>>       ...
>>>       #define LOCAL... REMOTE..
>>>       ...
>>>       #include <util/unwind-libunwind-local.c>
>>>       ...
>>>       ----
>>>
>>>       this way we will keep all the special setup for given unwind object
>>>       in one place and you can also use simple rule in the Build file like
>>>       without defining special rule:
>>>
>>>       libperf-$(CONFIG_LIBUNWIND_X86)      += unwind-libunwind_x86_32.o
>>>       libperf-$(CONFIG_LIBUNWIND_AARCH64)  += unwind-libunwind_arm64.o
>>>
>>>       the same way for the arch object:
>>>
>>>       arch/x86/util/unwind-libunwind-local.c
>>>       arch/x86/util/unwind-libunwind-x86_32.c
>>>
>>>
>>> Not sure I thought everything through, but I think this way
>>> we'll keep it more maintainable and readable..
>>>
>>> let me know what you think
>> The only concern is that, if later we support more platforms,
>> there will be too much files named as 'tools/perf/util/unwind-libunwind*.c'
>> Is it acceptable or not?
>>
>> And I thought all files belongs to specific archs should
>> go to folder under 'tools/perf/arch/xxx', is that right?
> hum, I wouldn't worry about that.. but you're right,
> let's put them under arch

But only 'tools/perf/arch/$(host platform)' will be built, in our case,
we should built the unwind-libunwind-$(arch) as long as we have
the remote libunwind libraries. So, I think there's a conflict in the
existing build script and not easy to 'put them under arch'. That's why
I choose a complex way in my previous patch.

Do you have some suggestions?
>
> thanks,
> jirka
>