Hello Julien, Thank you for the advice. I do have a follow up question.
On Thu, Apr 28, 2016 at 2:50 AM, Julien Grall <julien.gr...@arm.com> wrote: > Hello, > > On 27/04/16 23:53, Suriyan Ramasami wrote: > > How can I check which core is currently active? >> Judging by this link on big.LITTLE architecture: >> http://forum.odroid.com/viewtopic.php?f=65&t=2580 >> >> result of: cat /proc/cpuinfo | grep "CPU part" is >> CPU part : 0xc07 >> >> which stands for A7. >> >> If you do this in dom0, it will show all of them to be 0xc07. They are >> vCPUs after all. >> > > Which is not a good idea. This means that Linux is not able to detect > potential errata for the underlying cores (in this case the cortex-A15). > Also some userspace may do some runtime optimization based on the kind of > CPUs available in the guest. > > Xen is not ready for big.LITTLE, so I would highly recommend you to > disable either all the Cortex-A15 or Cortex-A7. > > Ian did recommend that if they were in their own cpu pools it would avoid mixing them in a guest. I was researching that angle. What is your take on that? If Linux is not recognizing it, that is a dom0/domU issue, is it not? Nonetheless, to start with, to add support, I think there would be less resistance if the boot cluster (a7) cpus are enabled and the other cluster disabled (a15) For your information, I am planning to send a patch to park any CPUs whose > MIDR is not matching the boot CPU one. > > Regards, > > -- > Julien Grall >
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