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Re: [Xen-devel] Odroid XU3 support

On Tue, Apr 26, 2016 at 3:31 AM, Julien Grall <julien.grall@xxxxxxx> wrote:
(CC the author of the Odroid support in Xen)

On 25/04/2016 11:01, Ivan Pavić2 wrote:


I have CCed Suriyan who added the support of Odroid in Xen. He might be able to help you here. 

i'm trying to boot dom0 linux on exynos5422 platform on A15 (big cpu cluster).
 From the past mailing lists on this link:
I'm not sure that is well defined how to change A7's for A15's.
Should change be in DTS or should one change cpu power up routines in linux?
So far every time it boots from A7's.

The Odroid XU3/XU4 afaict has a hardware pin which dictates if a A7 or an A15 core should boot up. It is currently set to boot up from the A7s.
Additionally, I found this in xen boot.ini file:

# use the A7s for dom0 and pin them to it
setenv xen_bootargs sync_console console=dtuart dtuart=/serial@12C20000 \
dom0_mem=800M dom0_max_vcpus=4 dom0_vcpus_pin

How this defines A7s for dom0?

As mentioned above, the hardware by design boots up from the A7 cluster. Hence, the first 4 cpus are A7s and the next 4 are the A15s.
How can I check which core is currently active?
Judging by this link on big.LITTLE architecture:

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.
I am not sure if I answered your question. Please feel free to probe more.


Julien Grall

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