Re: perf: multiple mmap of fd behavior on x86/ARM

Vince Weaver
2017-08-11T19:01:51Z

On Fri, 11 Aug 2017, Mark Rutland wrote:

> > This isn't some key thing that needs to be fixed, I was just curious about
> > the behavior difference between x86 and ARM.
>
> Sure; likewise I'm curious.

well I finally got a current git 64-bit kernel booted on the pi3.

Challenge: USB known to be broken currently, so no keyboard or ethernet.
Extra challenge: had the RX/TX lines switched on the serial connector.
Bonus challenge: the bcm2837 dts file doesn't enable armv8 PMU

I got through all of that, only to find:

$ uname -a
Linux pi3-git 4.13.0-rc4-00152-g2627393 #2 SMP PREEMPT Fri Aug 11 13:58:42 EDT 2017 aarch64 GNU/Linux

$ ./mmap_multiple
Trying to mmap same perf_event fd multiple times... PASSED

So maybe the issue was fixed between 4.9 and current?

Vince