Dovetail status clarification

Dovetail status clarification

[Stratiyenko Roman]

Hello xenomai community,

As you may already know kernel v5.4-rc1 released yesterday and according to
releases page on kernel.org this version is LTS.

So it make sense to start porting of xenomai to this release.

Some time ago dovetail were announced and It should replace ipipe for
xenomai.

Do you have any plans to start this migration in nearest time?

Best regards,
Roman Stratiienko

Re: Dovetail status clarification

[Jan Kiszka]

On 02.10.19 09:06, Stratiyenko Roman via Xenomai wrote:
> Hello xenomai community,
> 
> As you may already know kernel v5.4-rc1 released yesterday and according to
> releases page on kernel.org this version is LTS.
> 
> So it make sense to start porting of xenomai to this release.
> 
> Some time ago dovetail were announced and It should replace ipipe for
> xenomai.
> 
> Do you have any plans to start this migration in nearest time?

This is indeed a good question at the right time. Philippe can tell more details 
about the dovetail status. There are prototypes for ARM and x86 for Xenomai, but 
I didn't find time to test at least the x86 part so far. We should definitely 
look into this now before moving forward.

Jan

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

Re: Dovetail status clarification

[Philippe Gerum]

On 10/2/19 9:06 AM, Stratiyenko Roman wrote:
> Hello xenomai community,
> 
> As you may already know kernel v5.4-rc1 released yesterday and according
> to releases page on kernel.org <http://kernel.org> this version is LTS.
> 
> So it make sense to start porting of xenomai to this release. 
> 
> Some time ago dovetail were announced and It should replace ipipe for
> xenomai.
> 
> Do you have any plans to start this migration in nearest time?
> 

Dovetail currently runs 5.4-rc1 on x86_64, arm(v7) and armv8. Real-time
response and stability are routinely tested using EVL [1] which is the
reference rt core for Dovetail. Results look promising enough at this
stage for me not to consider porting the I-pipe/arm* to 5.4. I'd rather
contribute time and energy to improve Dovetail instead.

The initial groundwork for interfacing Xenomai 3 with Dovetail has
started some time ago by abstracting the I-pipe specific code from
Cobalt, since the current option is to allow enabling either I-pipe (for
pre-5.x kernels) or Dovetail at build time. I recently rebased that
stuff over the -next branch [2]. However, significant work remains to be
done for Dovetail support, including in libcobalt.

Switching to Dovetail will affect the ABI, so this would definitely be
post-3.1 material.

[1] https://evlproject.org/ports/
[2] https://lab.xenomai.org/xenomai-rpm.git/log/?h=wip/dovetail

-- 
Philippe.

Re: Dovetail status clarification

[Philippe Gerum]

On 10/2/19 10:12 AM, Jan Kiszka wrote:
> On 02.10.19 09:06, Stratiyenko Roman via Xenomai wrote:
>> Hello xenomai community,
>>
>> As you may already know kernel v5.4-rc1 released yesterday and
>> according to
>> releases page on kernel.org this version is LTS.
>>
>> So it make sense to start porting of xenomai to this release.
>>
>> Some time ago dovetail were announced and It should replace ipipe for
>> xenomai.
>>
>> Do you have any plans to start this migration in nearest time?
> 
> This is indeed a good question at the right time. Philippe can tell more
> details about the dovetail status. There are prototypes for ARM and x86
> for Xenomai, but I didn't find time to test at least the x86 part so
> far. We should definitely look into this now before moving forward.
> 

In a nutshell, Dovetail status is:

current target kernel: 5.4-rc1

x86_64: boots and runs EVL fine on the few Intel platforms I have at
hand, plus a couple of others as reported by an EVL user. A known bug
exists which may be related to (legacy) hardware which requires the
broadcast timer to come into play.

armv7: boots and runs EVL fine on the ref. hardware I mentioned in an
earlier mail.

armv8: boots and runs EVL fine. Will be part of a production system in
Q2 next year.

-- 
Philippe.