Re: User/kernel mode support in the various platforms

Will Deacon <[email protected]>
Newsgroups gmane.linux.oprofile
Message-ID <[email protected]>
Hi Carl,

On Mon, Dec 15, 2014 at 10:35:26PM +0000, Carl Love wrote:
> If you would let me know if the architecture you work on supports or 
> does not support user and kernel mode profiling, it would be greatly 
> appreciated.  Please run "uname -m" and let me know what the string 
> says so I can get the correct string into the patch.  
> 
> I need the information for a patch that I am working on OProfile 
> testsuite to skip the user/kernel scaling tests if the architecture
> doesn't support data in user mode only and kernel mode only.

On the ARM side, the following CPUs support mode exclusion:

  - armv7-ca15, camv7-ca7, armv7-krait
  - all armv8-* parts

Given that all future ARM cores will support it too, it might make more
sense (at least for us) to exclude cores that don't have it rather than
have an opt-in for every new CPU.

uname -m isn't sufficient to distinguish between these (which is why we
parse /proc/cpuinfo in _get_arm_cpu_type).

Will

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