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Subject: Re: [PATCH v3 3/7 UPDATE] perf tools: Add option for the path of
 buildid dsos under symfs
To: Hekuang <hekuang@huawei.com>, peterz@infradead.org, mingo@redhat.com,
        acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com,
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        tumanova@linux.vnet.ibm.com, kan.liang@intel.com, penberg@kernel.org
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Cc: linux-kernel@vger.kernel.org
From: David Ahern <dsahern@gmail.com>
Message-ID: <1193b9ba-7037-22c6-a54a-6992e155be46@gmail.com>
Date: Tue, 17 May 2016 19:51:29 -0600
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On 5/17/16 7:47 PM, Hekuang wrote:
>
>
> 在 2016/5/16 10:50, David Ahern 写道:
>> On 5/15/16 7:30 PM, Hekuang wrote:
>>> In previous patch, I use 'perf buildid-cache -a' to add vdso
>>> binary into the HOST buildid dir.
>>
>> So 'perf buildid-cache' needs the symfs option?
>>
>>
> With this patch 'PATCH v3 3/7 UPDATE', the tree of symfs dir is
> like this:
>
> ├── debug($(dso-prefix))
> │   ├── .build-id
> │   │   ├── 3a
> │   │   │   └── e5ba6d4e532ad529e43ccf1ce1ddf8a64a4fdd ->
> ../../[kernel.kallsyms]/3ae5ba6d4e532ad529e43ccf1ce1ddf8a64a4fdd
> │   │   └── 84
> │   │       └── dbd75729adba57cc42f5544b25de571c0c8731 ->
> ../../[vdso32]/84dbd75729adba57cc42f5544b25de571c0c8731
> │   ├── [kernel.kallsyms]
> │   │   └── 3ae5ba6d4e532ad529e43ccf1ce1ddf8a64a4fdd
> │   ├── [vdso]
> │   │   └── 84dbd75729adba57cc42f5544b25de571c0c8731
> │   └── [vdso32]
> │       └── 84dbd75729adba57cc42f5544b25de571c0c8731
> ├── lib
> │   ├── ld-2.22.so
> │   └── libc-2.22.so
> ├── tmp
> │   └── hello
> └── xxx
>
> So all binaries we need are included in the symfs dir. I think
> this is consistent with your idea explained in previous mails.
>
> With this symfs, we do not need buildid dir anymore and what's
> your idea on 'perf buildid-cache' needs symfs option? after all,
> that only effects on buildid dir.

I don't understand why dso-prefix option is needed? Why make me type yet 
more options to the analysis command? Why can't the directory be located 
under the symfs tree in a known location and populated the same way it 
is without symfs?