From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: perf probe and bitfields
Date: Fri, 26 Jan 2018 09:28:49 -0700
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 <20180126065656.GD22737@sejong>
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To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, Masami Hiramatsu <mhiramat@kernel.org>, Perf Users <linux-perf-users@vger.kernel.org>, kernel-team@lge.com

On 1/25/18 11:56 PM, Namhyung Kim wrote:
> Hi David,
> 
> On Fri, Jan 19, 2018 at 08:43:50AM -0800, David Ahern wrote:
>> Hi Arnaldo / Masami:
>>
>> Are there known issues / limitations with perf probe and bitfields?
>>
>> Here's an example: pkt_type is a bitfield in sk_buff. When I put a probe
>> in arp_rcv to examine the pkt_type value:
>>
>> $ perf probe 'arp_rcv ptype=skb->pkt_type dev=dev->name:string'
> 
> Bitfield type takes 3 parameters according to the Doc/perf-probe.txt.
> Maybe it's like 'ptype=skb->pkt_type:b3@0/8' ?

missed that. Thanks, Namyhung.