On 2017-10-30 11:07, Peng Fan wrote:
>>>>> Is Big.Little(A53+A72) supported?
>>>>
>>>> I didn't try, but I expect it work as long as all cores are exposed as
>>>> if they were equal.
>>>
>>> In my case A53 is the first cluster, A72 is in the second cluster. A72 runs
>>> faster that A53, so when enabling jailhouse, A72 will first finish 
>>> initializing jailhouse.
>>
>> Who is managing the cluster switch, Linux or something in firmware? In
>> order to let Jailhouse do its work properly, all cores need to be
>> enabled by it during setup, not just one cluster. IOW, all cores need to
>> be seen by Linux as individual cores.
> 
> firmware handles cluster.
> In my case it is
> CPU 4 ... OK (A72)
> CPU 5 ... OK (A72)
> CPU 2 ... OK (A53)
> CPU 3 ... OK (A53)
> CPU 0 ... OK (A53)
> CPU 1 ... OK (A53)
> 
> ....
> 
> When A53 backing to Linux side, A53 reports parking CPU. Jtag shows stage1 - 
> stage 2
> MMU table corrupt.

What is the exact error report along "Parking CPU ..."?

> 
> If I use JTAG to let CPU 4/5 later than CPU0/1/2/3, no corrupt.
> 
> Since there is a small hardware issue now, I could not make sure 
> software/hardware
> issue. I'll continue debug.

Well, there is always the risk that we need some special hardware quirk
workaround or that there is actually an architectural difference in the
A53/A72 setups that we still miss. A53 is pretty mature regarding
Jailhouse now, but A72 is new.

[...]

>>>>
>>>> Which RTOS do you have in mind, a commercial one or some open source
>>>> project?
>>>
>>> I would like to use open source projects, such as RTEMS. But graphic support
>>> is not that good. Also AArch64 support is not ready.
>>> Do you have some recommendation except RTEMS? And if using rtos as root 
>>> cell, do you have
>>> some ideas how to proceed, seems jailhouse now heavily relys on Linux?
>>
>> I don't know which open source RTOS is already running well in AArch64
>> mode. We were discussing Zephyr as potential boot loader for Jailhouse,
>> but that is also only supporting 32-bit mode so far. It seems to gain
>> x86-64 support soon, and that may open it up for AArch64 as well.
> 
> As far as I know, Zephyr is mainly for IoT usage and ARM Cortex-A is not
> supported. I'll give a try on RTEMS first.

Yes, there is some work missing to enable a Cortex-A in Zephyr, but
that's all not a lot of code - just check how small the inmates are that
Jailhouse provides for ARMv7 and v8. RTEMS should work but has its
oddities as well.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux

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