Date: Tue, 4 Nov 2014 19:40:31 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Pawel Moll <pawel.moll@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>,
        Richard Cochran <richardcochran@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>,
        Paul Mackerras <paulus@samba.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        John Stultz <john.stultz@linaro.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Christopher Covington <cov@codeaurora.org>,
        David Ahern <dsahern@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
        Tomeu Vizoso <tomeu@tomeuvizoso.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-api@vger.kernel.org" <linux-api@vger.kernel.org>
Subject: Re: [PATCH v3 2/3] perf: Userspace event
Message-ID: <20141104184031.GM10501@worktop.programming.kicks-ass.net>
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On Tue, Nov 04, 2014 at 04:42:11PM +0000, Pawel Moll wrote:
> 
> 1. I'm wrong and the record doesn't have to be padded to make it 8 bytes
> aligned. Then I can drop the additional size field.

No, you're right, we're supposed to stay 8 byte aligned.

> 2. I could impose a limitation on the prctl API that the data size must
> be 8 bytes aligned. Bad idea in my opinion, I'd rather not.

Agreed.

> 3. The additional size (for the data part) field stays. Notice that
> PERF_SAMPLE_RAW has it as well :-)

Right, with binary data there is no other day. With \0 terminated
strings there won't be a problem, but I think we decided we wanted to
allow any binary blow.
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