On 2017-06-08 18:48, Gustavo Lima Chaves wrote:
>> We are currently evaluating Zephyr on Jailhouse, but that is still in a
>> too early stage to contribute to this discussion or even a decision. How
>> urgent is the topic for you?
> 
> How far are you into Zephyr? I have patches doing a preliminar port, so that
> at least UART and LOAPIC timers are working from Zephyr just fine:
> 
> """
> Created cell "tiny-demo"
> Page pool usage after cell creation: mem 275/1480, remap 65607/131072
> Cell "tiny-demo" can be loaded
> CPU 3 received SIPI, vector 100
> Started cell "tiny-demo"
> ***** BOOTING ZEPHYR OS v1.7.99 - BUILD: Jun  8 2017 00:36:18 *****
> Hello World!
> Hello World!
> Hello World!
> """
> 

Hoho, good that I dropped this note - great to see this!

I added Andreas to CC who is just starting off, maybe still a bit wet
from the first bucket of cold Jailhouse water.

> This code lies on my hard disk only, for now, but sure I want to make
> it upstream, if both parties agree on its usefulness (Zephyr and
> Jailhouse). From a licensing POV, I just used a bare minimal excerpt
> from header-32.S, and would indeed be great to have that code more
> permissive, so that I would not have to bother re-writing it myself.

Individual files would be easier to relicense, header-32.S is only owned
by us e.g.

> 
> One thing I lost from not using the inmate lib was xAPIC access to the
> LOAPIC, so my preliminar patch does rewrite those accesses to be
> x2APIC (MSR-based).

x2APIC is the better choice.

But back to the topic, and actually there are two: writing applications
on top of a permissive runtime - inmates lib or a permissively licensed
RTOS - and providing reusable material to porting RTOSes over Jailhouse.
When doing a relicensing, the motivation and intended usage should be
clearly defined before approaching all the copyright holders. And we
should then also think about how to (re-)structure the code when we want
to support the second case.

How much could Zephyr be configured down in order to become something
like the inmates lib? In fact, if it can server all existing purposes -
simple tests, benchmarks, demos - and be scaled up to a real application
platform, I would like to avoid doing work twice. Then our focus should
be enabling Jailhouse for Zephyr on all our supported archs.

Jan

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

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