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Date: Fri, 12 Sep 2014 10:00:09 -0400
From: Christopher Covington <cov@codeaurora.org>
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To: Pawel Moll <pawel.moll@arm.com>
CC: Richard Cochran <richardcochran@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
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Subject: Re: [RFC 2/2] perf: Marker software event and ioctl
References: <1410522513-1045-1-git-send-email-pawel.moll@arm.com>  <1410522513-1045-3-git-send-email-pawel.moll@arm.com>  <5412EA7A.9020807@codeaurora.org> <1410526672.16936.52.camel@hornet>
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On 09/12/2014 08:57 AM, Pawel Moll wrote:
> On Fri, 2014-09-12 at 13:43 +0100, Christopher Covington wrote:
>> Just to ask the dumb questions in case the answers I've come up with are
>> wrong: What is PAGE_SIZE on an arm64 kernel? 
> 
> It's either 4 or 64k, depending on CONFIG_ARM64_64K_PAGES.
> 
>> How does userspace know?
>>
> #include <unistd.h>
> #include <stdio.h>
> 
> int main(void)
> {
> 	printf("%ld\n", sysconf(_SC_PAGESIZE));
> 	return 0;
> }

Oh excellent, that actually works. Based on a misreading of the glibc code I
thought it was hard-coded to 64K.

Thanks,
Christopher

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