[Xenomai] arm imx6 and hardware FPU

[Xenomai] arm imx6 and hardware FPU

[Paolo Minazzi]

Hi to all,
I'm trying to test my imx6 with xenomai 2.6.3.
I use the linaro cross-compiler that uses the hardware floating point.

I made a simple floating point test.

If I use two non-realtime user-space tasks the test works OK and I have 
no errors in calculations.
This means that compiler and hardware works well.

But I I use two realtime user-space tasks I have errors in calculations.
Real-time tasks are created with rt_task_create(&demo, "demo", 0, 99, 
T_FPU);


This is my kernel config
============================================
...
#
# Machine
#
CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
CONFIG_IPIPE_WANT_ACTIVE_MM=y
CONFIG_XENO_HW_FPU=y
CONFIG_XENO_HW_UNLOCKED_SWITCH=y
...
#
# At least one emulation must be selected
#
CONFIG_VFP=y
CONFIG_VFPv3=y
CONFIG_NEON=y
CONFIG_VFP_3_2_BACKPORT=y
...
============================================

Is it possible to use ***hardware floating point*** with realtime 
user-space tasks ?

Regards,
Paolo Minazzi

Re: [Xenomai] arm imx6 and hardware FPU

[Gilles Chanteperdrix]

On 04/11/2014 01:44 PM, Paolo Minazzi wrote:
> Hi to all,
> I'm trying to test my imx6 with xenomai 2.6.3.
> I use the linaro cross-compiler that uses the hardware floating point.
>
> I made a simple floating point test.
>
> If I use two non-realtime user-space tasks the test works OK and I have
> no errors in calculations.
> This means that compiler and hardware works well.
>
> But I I use two realtime user-space tasks I have errors in calculations.
> Real-time tasks are created with rt_task_create(&demo, "demo", 0, 99,
> T_FPU);
>
>
> This is my kernel config
> ============================================
> ...
> #
> # Machine
> #
> CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
> CONFIG_IPIPE_WANT_ACTIVE_MM=y
> CONFIG_XENO_HW_FPU=y
> CONFIG_XENO_HW_UNLOCKED_SWITCH=y
> ...
> #
> # At least one emulation must be selected
> #
> CONFIG_VFP=y
> CONFIG_VFPv3=y
> CONFIG_NEON=y
> CONFIG_VFP_3_2_BACKPORT=y
> ...
> ============================================
>
> Is it possible to use ***hardware floating point*** with realtime
> user-space tasks ?

Yes, it should be. Do you get the same issue when running both the 
switchtest and switchtest -s 1000 tests? Do you have the same issue with 
the I-pipe patch for Linux 3.8?


-- 
					    Gilles.

Re: [Xenomai] arm imx6 and hardware FPU

[Paolo Minazzi]

Il 11/04/2014 13.49, Gilles Chanteperdrix ha scritto:
> On 04/11/2014 01:44 PM, Paolo Minazzi wrote:
>> Hi to all,
>> I'm trying to test my imx6 with xenomai 2.6.3.
>> I use the linaro cross-compiler that uses the hardware floating point.
>>
>> I made a simple floating point test.
>>
>> If I use two non-realtime user-space tasks the test works OK and I have
>> no errors in calculations.
>> This means that compiler and hardware works well.
>>
>> But I I use two realtime user-space tasks I have errors in calculations.
>> Real-time tasks are created with rt_task_create(&demo, "demo", 0, 99,
>> T_FPU);
>>
>>
>> This is my kernel config
>> ============================================
>> ...
>> #
>> # Machine
>> #
>> CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
>> CONFIG_IPIPE_WANT_ACTIVE_MM=y
>> CONFIG_XENO_HW_FPU=y
>> CONFIG_XENO_HW_UNLOCKED_SWITCH=y
>> ...
>> #
>> # At least one emulation must be selected
>> #
>> CONFIG_VFP=y
>> CONFIG_VFPv3=y
>> CONFIG_NEON=y
>> CONFIG_VFP_3_2_BACKPORT=y
>> ...
>> ============================================
>>
>> Is it possible to use ***hardware floating point*** with realtime
>> user-space tasks ?
>
> Yes, it should be. Do you get the same issue when running both the 
> switchtest and switchtest -s 1000 tests? Do you have the same issue 
> with the I-pipe patch for Linux 3.8?
>
>
/ # ./switchtest -s 1000
== Testing FPU check routines...
d0: 1 != 2
d1: 1 != 2
d2: 1 != 2
d3: 1 != 2
d4: 1 != 2
d5: 1 != 2
d6: 1 != 2
d7: 1 != 2
d8: 1 != 2
d9: 1 != 2
d10: 1 != 2
d11: 1 != 2
d12: 1 != 2
d13: 1 != 2
d14: 1 != 2
d15: 1 != 2
== FPU check routines: OK.

/ # ./switchtest
== Testing FPU check routines...
d0: 1 != 2
d1: 1 != 2
d2: 1 != 2
d3: 1 != 2
d4: 1 != 2
d5: 1 != 2
d6: 1 != 2
d7: 1 != 2
d8: 1 != 2
d9: 1 != 2
d10: 1 != 2
d11: 1 != 2
d12: 1 != 2
d13: 1 != 2
d14: 1 != 2
d15: 1 != 2
== FPU check routines: OK.

As you can see the test seems OK.
But If I understand correctly switchtest is not a real-time test.

I see the problem If I use my floating point test.
I try to calculate sin(2x).
Then I claculate 2*sin(x)*cos(x).
They should be similar. But sometime they are very different ===> fpu error


I have kerne 3.0.35.
For me it is not so easy try 3.8.

Paolo

Re: [Xenomai] arm imx6 and hardware FPU

[Gilles Chanteperdrix]

On 04/11/2014 02:15 PM, Paolo Minazzi wrote:
> Il 11/04/2014 13.49, Gilles Chanteperdrix ha scritto:
>> On 04/11/2014 01:44 PM, Paolo Minazzi wrote:
>>> Hi to all,
>>> I'm trying to test my imx6 with xenomai 2.6.3.
>>> I use the linaro cross-compiler that uses the hardware floating point.
>>>
>>> I made a simple floating point test.
>>>
>>> If I use two non-realtime user-space tasks the test works OK and I have
>>> no errors in calculations.
>>> This means that compiler and hardware works well.
>>>
>>> But I I use two realtime user-space tasks I have errors in calculations.
>>> Real-time tasks are created with rt_task_create(&demo, "demo", 0, 99,
>>> T_FPU);
>>>
>>>
>>> This is my kernel config
>>> ============================================
>>> ...
>>> #
>>> # Machine
>>> #
>>> CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
>>> CONFIG_IPIPE_WANT_ACTIVE_MM=y
>>> CONFIG_XENO_HW_FPU=y
>>> CONFIG_XENO_HW_UNLOCKED_SWITCH=y
>>> ...
>>> #
>>> # At least one emulation must be selected
>>> #
>>> CONFIG_VFP=y
>>> CONFIG_VFPv3=y
>>> CONFIG_NEON=y
>>> CONFIG_VFP_3_2_BACKPORT=y
>>> ...
>>> ============================================
>>>
>>> Is it possible to use ***hardware floating point*** with realtime
>>> user-space tasks ?
>>
>> Yes, it should be. Do you get the same issue when running both the
>> switchtest and switchtest -s 1000 tests? Do you have the same issue
>> with the I-pipe patch for Linux 3.8?
>>
>>
> / # ./switchtest -s 1000
> == Testing FPU check routines...
> d0: 1 != 2
> d1: 1 != 2
> d2: 1 != 2
> d3: 1 != 2
> d4: 1 != 2
> d5: 1 != 2
> d6: 1 != 2
> d7: 1 != 2
> d8: 1 != 2
> d9: 1 != 2
> d10: 1 != 2
> d11: 1 != 2
> d12: 1 != 2
> d13: 1 != 2
> d14: 1 != 2
> d15: 1 != 2
> == FPU check routines: OK.
>
> / # ./switchtest
> == Testing FPU check routines...
> d0: 1 != 2
> d1: 1 != 2
> d2: 1 != 2
> d3: 1 != 2
> d4: 1 != 2
> d5: 1 != 2
> d6: 1 != 2
> d7: 1 != 2
> d8: 1 != 2
> d9: 1 != 2
> d10: 1 != 2
> d11: 1 != 2
> d12: 1 != 2
> d13: 1 != 2
> d14: 1 != 2
> d15: 1 != 2
> == FPU check routines: OK.
>
> As you can see the test seems OK.
> But If I understand correctly switchtest is not a real-time test.

You do not understand correctly. You should run
switchtest & switchtest -s 1000

And let them run for some time.

> I see the problem If I use my floating point test.
> I try to calculate sin(2x).
> Then I claculate 2*sin(x)*cos(x).
> They should be similar. But sometime they are very different ===> fpu error
>
>
> I have kerne 3.0.35.
> For me it is not so easy try 3.8.

How is that? To test xenomai you do not need all the drivers, just the uart.


-- 
					    Gilles.

Re: [Xenomai] arm imx6 and hardware FPU

[Paolo Minazzi]

Il 11/04/2014 15.15, Gilles Chanteperdrix ha scritto:
> On 04/11/2014 03:05 PM, Paolo Minazzi wrote:
>> Il 11/04/2014 14.45, Gilles Chanteperdrix ha scritto:
>>> On 04/11/2014 02:32 PM, Paolo Minazzi wrote:
>>>> Il 11/04/2014 14.24, Gilles Chanteperdrix ha scritto:
>>>>> On 04/11/2014 02:15 PM, Paolo Minazzi wrote:
>>>>>> Il 11/04/2014 13.49, Gilles Chanteperdrix ha scritto:
>>>>>>> On 04/11/2014 01:44 PM, Paolo Minazzi wrote:
>>>>>>>> Hi to all,
>>>>>>>> I'm trying to test my imx6 with xenomai 2.6.3.
>>>>>>>> I use the linaro cross-compiler that uses the hardware floating
>>>>>>>> point.
>>>>>>>>
>>>>>>>> I made a simple floating point test.
>>>>>>>>
>>>>>>>> If I use two non-realtime user-space tasks the test works OK and I
>>>>>>>> have
>>>>>>>> no errors in calculations.
>>>>>>>> This means that compiler and hardware works well.
>>>>>>>>
>>>>>>>> But I I use two realtime user-space tasks I have errors in
>>>>>>>> calculations.
>>>>>>>> Real-time tasks are created with rt_task_create(&demo, "demo", 0,
>>>>>>>> 99,
>>>>>>>> T_FPU);
>>>>>>>>
>>>>>>>>
>>>>>>>> This is my kernel config
>>>>>>>> ============================================
>>>>>>>> ...
>>>>>>>> #
>>>>>>>> # Machine
>>>>>>>> #
>>>>>>>> CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
>>>>>>>> CONFIG_IPIPE_WANT_ACTIVE_MM=y
>>>>>>>> CONFIG_XENO_HW_FPU=y
>>>>>>>> CONFIG_XENO_HW_UNLOCKED_SWITCH=y
>>>>>>>> ...
>>>>>>>> #
>>>>>>>> # At least one emulation must be selected
>>>>>>>> #
>>>>>>>> CONFIG_VFP=y
>>>>>>>> CONFIG_VFPv3=y
>>>>>>>> CONFIG_NEON=y
>>>>>>>> CONFIG_VFP_3_2_BACKPORT=y
>>>>>>>> ...
>>>>>>>> ============================================
>>>>>>>>
>>>>>>>> Is it possible to use ***hardware floating point*** with realtime
>>>>>>>> user-space tasks ?
>>>>>>>
>>>>>>> Yes, it should be. Do you get the same issue when running both the
>>>>>>> switchtest and switchtest -s 1000 tests? Do you have the same issue
>>>>>>> with the I-pipe patch for Linux 3.8?
>>>>>>>
>>>>>>>
>>>>>> / # ./switchtest -s 1000
>>>>>> == Testing FPU check routines...
>>>>>> d0: 1 != 2
>>>>>> d1: 1 != 2
>>>>>> d2: 1 != 2
>>>>>> d3: 1 != 2
>>>>>> d4: 1 != 2
>>>>>> d5: 1 != 2
>>>>>> d6: 1 != 2
>>>>>> d7: 1 != 2
>>>>>> d8: 1 != 2
>>>>>> d9: 1 != 2
>>>>>> d10: 1 != 2
>>>>>> d11: 1 != 2
>>>>>> d12: 1 != 2
>>>>>> d13: 1 != 2
>>>>>> d14: 1 != 2
>>>>>> d15: 1 != 2
>>>>>> == FPU check routines: OK.
>>>>>>
>>>>>> / # ./switchtest
>>>>>> == Testing FPU check routines...
>>>>>> d0: 1 != 2
>>>>>> d1: 1 != 2
>>>>>> d2: 1 != 2
>>>>>> d3: 1 != 2
>>>>>> d4: 1 != 2
>>>>>> d5: 1 != 2
>>>>>> d6: 1 != 2
>>>>>> d7: 1 != 2
>>>>>> d8: 1 != 2
>>>>>> d9: 1 != 2
>>>>>> d10: 1 != 2
>>>>>> d11: 1 != 2
>>>>>> d12: 1 != 2
>>>>>> d13: 1 != 2
>>>>>> d14: 1 != 2
>>>>>> d15: 1 != 2
>>>>>> == FPU check routines: OK.
>>>>>>
>>>>>> As you can see the test seems OK.
>>>>>> But If I understand correctly switchtest is not a real-time test.
>>>>>
>>>>> You do not understand correctly. You should run
>>>>> switchtest & switchtest -s 1000
>>>>>
>>>>> And let them run for some time.
>>>>>
>>>>>> I see the problem If I use my floating point test.
>>>>>> I try to calculate sin(2x).
>>>>>> Then I claculate 2*sin(x)*cos(x).
>>>>>> They should be similar. But sometime they are very different ===> 
>>>>>> fpu
>>>>>> error
>>>>>>
>>>>>>
>>>>>> I have kerne 3.0.35.
>>>>>> For me it is not so easy try 3.8.
>>>>>
>>>>> How is that? To test xenomai you do not need all the drivers, just 
>>>>> the
>>>>> uart.
>>>>>
>>>>>
>>>> I'm able to do it.
>>>> But I'm paid for use this board. Try I cannot loose too time to test
>>>> configurations that we will not use.
>>>> I understand you, but you should try to understand me.
>>>> Have you got some ideas ?
>>>
>>> I have given you my ideas. Of course, you are free to ignore them and
>>> debug the issue on your own.
>>>
>>>
>> I understand your hard words.
>> I understand only because in my life I worked (in my free time) on a
>> very complex project : colinux64.
>> If you do not know, colinux is a porting of linux kernel on windows.
>> Only who works on these complex parts of the system know the hard works
>> there is to do and what it means find bug. The same complexity of 
>> xenomai.
>>
>> I have done my homework, but not in xenomai project world.
>> Repeat, I understand your words ... but remember that not all the people
>> are stupid and do not want to find bug.
>> You do not know the skills of the persons on the other side, so my
>> advice is to try to understand which kind of person you are contacting.
>> It is not so easy ... but it could be important in your work.
>
> What are you talking about? You ask a question, I reply rapidly with 
> some ideas to test. You do not want to test these ideas, so the 
> conclusion is: debug the issue on your own. I do not know any other 
> answer than the one I gave you.
>
>
Studying the problem it seems that xenomai works fine.
The problem maybe is related to not re-entrance of sin and cos function.
If I use simple float operation I do not see the problem.

I have the same problem using two non realtime task, so I can say that 
the problem is not related to xenomai.

Regards
Paolo

Re: [Xenomai] arm imx6 and hardware FPU

[Gilles Chanteperdrix]

On 04/17/2014 02:20 PM, Paolo Minazzi wrote:
> Il 11/04/2014 15.15, Gilles Chanteperdrix ha scritto:
>> On 04/11/2014 03:05 PM, Paolo Minazzi wrote:
>>> Il 11/04/2014 14.45, Gilles Chanteperdrix ha scritto:
>>>> On 04/11/2014 02:32 PM, Paolo Minazzi wrote:
>>>>> Il 11/04/2014 14.24, Gilles Chanteperdrix ha scritto:
>>>>>> On 04/11/2014 02:15 PM, Paolo Minazzi wrote:
>>>>>>> Il 11/04/2014 13.49, Gilles Chanteperdrix ha scritto:
>>>>>>>> On 04/11/2014 01:44 PM, Paolo Minazzi wrote:
>>>>>>>>> Hi to all,
>>>>>>>>> I'm trying to test my imx6 with xenomai 2.6.3.
>>>>>>>>> I use the linaro cross-compiler that uses the hardware floating
>>>>>>>>> point.
>>>>>>>>>
>>>>>>>>> I made a simple floating point test.
>>>>>>>>>
>>>>>>>>> If I use two non-realtime user-space tasks the test works OK and I
>>>>>>>>> have
>>>>>>>>> no errors in calculations.
>>>>>>>>> This means that compiler and hardware works well.
>>>>>>>>>
>>>>>>>>> But I I use two realtime user-space tasks I have errors in
>>>>>>>>> calculations.
>>>>>>>>> Real-time tasks are created with rt_task_create(&demo, "demo", 0,
>>>>>>>>> 99,
>>>>>>>>> T_FPU);
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> This is my kernel config
>>>>>>>>> ============================================
>>>>>>>>> ...
>>>>>>>>> #
>>>>>>>>> # Machine
>>>>>>>>> #
>>>>>>>>> CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
>>>>>>>>> CONFIG_IPIPE_WANT_ACTIVE_MM=y
>>>>>>>>> CONFIG_XENO_HW_FPU=y
>>>>>>>>> CONFIG_XENO_HW_UNLOCKED_SWITCH=y
>>>>>>>>> ...
>>>>>>>>> #
>>>>>>>>> # At least one emulation must be selected
>>>>>>>>> #
>>>>>>>>> CONFIG_VFP=y
>>>>>>>>> CONFIG_VFPv3=y
>>>>>>>>> CONFIG_NEON=y
>>>>>>>>> CONFIG_VFP_3_2_BACKPORT=y
>>>>>>>>> ...
>>>>>>>>> ============================================
>>>>>>>>>
>>>>>>>>> Is it possible to use ***hardware floating point*** with realtime
>>>>>>>>> user-space tasks ?
>>>>>>>>
>>>>>>>> Yes, it should be. Do you get the same issue when running both the
>>>>>>>> switchtest and switchtest -s 1000 tests? Do you have the same issue
>>>>>>>> with the I-pipe patch for Linux 3.8?
>>>>>>>>
>>>>>>>>
>>>>>>> / # ./switchtest -s 1000
>>>>>>> == Testing FPU check routines...
>>>>>>> d0: 1 != 2
>>>>>>> d1: 1 != 2
>>>>>>> d2: 1 != 2
>>>>>>> d3: 1 != 2
>>>>>>> d4: 1 != 2
>>>>>>> d5: 1 != 2
>>>>>>> d6: 1 != 2
>>>>>>> d7: 1 != 2
>>>>>>> d8: 1 != 2
>>>>>>> d9: 1 != 2
>>>>>>> d10: 1 != 2
>>>>>>> d11: 1 != 2
>>>>>>> d12: 1 != 2
>>>>>>> d13: 1 != 2
>>>>>>> d14: 1 != 2
>>>>>>> d15: 1 != 2
>>>>>>> == FPU check routines: OK.
>>>>>>>
>>>>>>> / # ./switchtest
>>>>>>> == Testing FPU check routines...
>>>>>>> d0: 1 != 2
>>>>>>> d1: 1 != 2
>>>>>>> d2: 1 != 2
>>>>>>> d3: 1 != 2
>>>>>>> d4: 1 != 2
>>>>>>> d5: 1 != 2
>>>>>>> d6: 1 != 2
>>>>>>> d7: 1 != 2
>>>>>>> d8: 1 != 2
>>>>>>> d9: 1 != 2
>>>>>>> d10: 1 != 2
>>>>>>> d11: 1 != 2
>>>>>>> d12: 1 != 2
>>>>>>> d13: 1 != 2
>>>>>>> d14: 1 != 2
>>>>>>> d15: 1 != 2
>>>>>>> == FPU check routines: OK.
>>>>>>>
>>>>>>> As you can see the test seems OK.
>>>>>>> But If I understand correctly switchtest is not a real-time test.
>>>>>>
>>>>>> You do not understand correctly. You should run
>>>>>> switchtest & switchtest -s 1000
>>>>>>
>>>>>> And let them run for some time.
>>>>>>
>>>>>>> I see the problem If I use my floating point test.
>>>>>>> I try to calculate sin(2x).
>>>>>>> Then I claculate 2*sin(x)*cos(x).
>>>>>>> They should be similar. But sometime they are very different ===>
>>>>>>> fpu
>>>>>>> error
>>>>>>>
>>>>>>>
>>>>>>> I have kerne 3.0.35.
>>>>>>> For me it is not so easy try 3.8.
>>>>>>
>>>>>> How is that? To test xenomai you do not need all the drivers, just
>>>>>> the
>>>>>> uart.
>>>>>>
>>>>>>
>>>>> I'm able to do it.
>>>>> But I'm paid for use this board. Try I cannot loose too time to test
>>>>> configurations that we will not use.
>>>>> I understand you, but you should try to understand me.
>>>>> Have you got some ideas ?
>>>>
>>>> I have given you my ideas. Of course, you are free to ignore them and
>>>> debug the issue on your own.
>>>>
>>>>
>>> I understand your hard words.
>>> I understand only because in my life I worked (in my free time) on a
>>> very complex project : colinux64.
>>> If you do not know, colinux is a porting of linux kernel on windows.
>>> Only who works on these complex parts of the system know the hard works
>>> there is to do and what it means find bug. The same complexity of
>>> xenomai.
>>>
>>> I have done my homework, but not in xenomai project world.
>>> Repeat, I understand your words ... but remember that not all the people
>>> are stupid and do not want to find bug.
>>> You do not know the skills of the persons on the other side, so my
>>> advice is to try to understand which kind of person you are contacting.
>>> It is not so easy ... but it could be important in your work.
>>
>> What are you talking about? You ask a question, I reply rapidly with
>> some ideas to test. You do not want to test these ideas, so the
>> conclusion is: debug the issue on your own. I do not know any other
>> answer than the one I gave you.
>>
>>
> Studying the problem it seems that xenomai works fine.
> The problem maybe is related to not re-entrance of sin and cos function.
> If I use simple float operation I do not see the problem.
>
> I have the same problem using two non realtime task, so I can say that
> the problem is not related to xenomai.

In order to be sure that the bug is not introduced by Xenomai, you 
should disable CONFIG_XENOMAI, CONFIG_IPIPE, and in fact, even try the 
unpatched kernel. And again: you can use the switchtest tool to test 
whether FPU is OK (with CONFIG_XENOMAI), and if switchtest fails after 
some time, we have tools to make debugging much easier.

Also note that the 3.0 kernel was released more than 3 years ago, so it 
is entirely possible that mainline bugs have been fixed since then, both 
on Linux side, and on I-pipe side, which is the reason I asked you to 
test a more recent kernel.

-- 
					    Gilles.

Re: [Xenomai] arm imx6 and hardware FPU [SOLVED]

[Paolo Minazzi]

Il 17/04/2014 15.33, Gilles Chanteperdrix ha scritto:
> On 04/17/2014 02:20 PM, Paolo Minazzi wrote:
>> Il 11/04/2014 15.15, Gilles Chanteperdrix ha scritto:
>>> On 04/11/2014 03:05 PM, Paolo Minazzi wrote:
>>>> Il 11/04/2014 14.45, Gilles Chanteperdrix ha scritto:
>>>>> On 04/11/2014 02:32 PM, Paolo Minazzi wrote:
>>>>>> Il 11/04/2014 14.24, Gilles Chanteperdrix ha scritto:
>>>>>>> On 04/11/2014 02:15 PM, Paolo Minazzi wrote:
>>>>>>>> Il 11/04/2014 13.49, Gilles Chanteperdrix ha scritto:
>>>>>>>>> On 04/11/2014 01:44 PM, Paolo Minazzi wrote:
>>>>>>>>>> Hi to all,
>>>>>>>>>> I'm trying to test my imx6 with xenomai 2.6.3.
>>>>>>>>>> I use the linaro cross-compiler that uses the hardware floating
>>>>>>>>>> point.
>>>>>>>>>>
>>>>>>>>>> I made a simple floating point test.
>>>>>>>>>>
>>>>>>>>>> If I use two non-realtime user-space tasks the test works OK 
>>>>>>>>>> and I
>>>>>>>>>> have
>>>>>>>>>> no errors in calculations.
>>>>>>>>>> This means that compiler and hardware works well.
>>>>>>>>>>
>>>>>>>>>> But I I use two realtime user-space tasks I have errors in
>>>>>>>>>> calculations.
>>>>>>>>>> Real-time tasks are created with rt_task_create(&demo, 
>>>>>>>>>> "demo", 0,
>>>>>>>>>> 99,
>>>>>>>>>> T_FPU);
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> This is my kernel config
>>>>>>>>>> ============================================
>>>>>>>>>> ...
>>>>>>>>>> #
>>>>>>>>>> # Machine
>>>>>>>>>> #
>>>>>>>>>> CONFIG_IPIPE_WANT_PREEMPTIBLE_SWITCH=y
>>>>>>>>>> CONFIG_IPIPE_WANT_ACTIVE_MM=y
>>>>>>>>>> CONFIG_XENO_HW_FPU=y
>>>>>>>>>> CONFIG_XENO_HW_UNLOCKED_SWITCH=y
>>>>>>>>>> ...
>>>>>>>>>> #
>>>>>>>>>> # At least one emulation must be selected
>>>>>>>>>> #
>>>>>>>>>> CONFIG_VFP=y
>>>>>>>>>> CONFIG_VFPv3=y
>>>>>>>>>> CONFIG_NEON=y
>>>>>>>>>> CONFIG_VFP_3_2_BACKPORT=y
>>>>>>>>>> ...
>>>>>>>>>> ============================================
>>>>>>>>>>
>>>>>>>>>> Is it possible to use ***hardware floating point*** with 
>>>>>>>>>> realtime
>>>>>>>>>> user-space tasks ?
>>>>>>>>>
>>>>>>>>> Yes, it should be. Do you get the same issue when running both 
>>>>>>>>> the
>>>>>>>>> switchtest and switchtest -s 1000 tests? Do you have the same 
>>>>>>>>> issue
>>>>>>>>> with the I-pipe patch for Linux 3.8?
>>>>>>>>>
>>>>>>>>>
>>>>>>>> / # ./switchtest -s 1000
>>>>>>>> == Testing FPU check routines...
>>>>>>>> d0: 1 != 2
>>>>>>>> d1: 1 != 2
>>>>>>>> d2: 1 != 2
>>>>>>>> d3: 1 != 2
>>>>>>>> d4: 1 != 2
>>>>>>>> d5: 1 != 2
>>>>>>>> d6: 1 != 2
>>>>>>>> d7: 1 != 2
>>>>>>>> d8: 1 != 2
>>>>>>>> d9: 1 != 2
>>>>>>>> d10: 1 != 2
>>>>>>>> d11: 1 != 2
>>>>>>>> d12: 1 != 2
>>>>>>>> d13: 1 != 2
>>>>>>>> d14: 1 != 2
>>>>>>>> d15: 1 != 2
>>>>>>>> == FPU check routines: OK.
>>>>>>>>
>>>>>>>> / # ./switchtest
>>>>>>>> == Testing FPU check routines...
>>>>>>>> d0: 1 != 2
>>>>>>>> d1: 1 != 2
>>>>>>>> d2: 1 != 2
>>>>>>>> d3: 1 != 2
>>>>>>>> d4: 1 != 2
>>>>>>>> d5: 1 != 2
>>>>>>>> d6: 1 != 2
>>>>>>>> d7: 1 != 2
>>>>>>>> d8: 1 != 2
>>>>>>>> d9: 1 != 2
>>>>>>>> d10: 1 != 2
>>>>>>>> d11: 1 != 2
>>>>>>>> d12: 1 != 2
>>>>>>>> d13: 1 != 2
>>>>>>>> d14: 1 != 2
>>>>>>>> d15: 1 != 2
>>>>>>>> == FPU check routines: OK.
>>>>>>>>
>>>>>>>> As you can see the test seems OK.
>>>>>>>> But If I understand correctly switchtest is not a real-time test.
>>>>>>>
>>>>>>> You do not understand correctly. You should run
>>>>>>> switchtest & switchtest -s 1000
>>>>>>>
>>>>>>> And let them run for some time.
>>>>>>>
>>>>>>>> I see the problem If I use my floating point test.
>>>>>>>> I try to calculate sin(2x).
>>>>>>>> Then I claculate 2*sin(x)*cos(x).
>>>>>>>> They should be similar. But sometime they are very different ===>
>>>>>>>> fpu
>>>>>>>> error
>>>>>>>>
>>>>>>>>
>>>>>>>> I have kerne 3.0.35.
>>>>>>>> For me it is not so easy try 3.8.
>>>>>>>
>>>>>>> How is that? To test xenomai you do not need all the drivers, just
>>>>>>> the
>>>>>>> uart.
>>>>>>>
>>>>>>>
>>>>>> I'm able to do it.
>>>>>> But I'm paid for use this board. Try I cannot loose too time to test
>>>>>> configurations that we will not use.
>>>>>> I understand you, but you should try to understand me.
>>>>>> Have you got some ideas ?
>>>>>
>>>>> I have given you my ideas. Of course, you are free to ignore them and
>>>>> debug the issue on your own.
>>>>>
>>>>>
>>>> I understand your hard words.
>>>> I understand only because in my life I worked (in my free time) on a
>>>> very complex project : colinux64.
>>>> If you do not know, colinux is a porting of linux kernel on windows.
>>>> Only who works on these complex parts of the system know the hard 
>>>> works
>>>> there is to do and what it means find bug. The same complexity of
>>>> xenomai.
>>>>
>>>> I have done my homework, but not in xenomai project world.
>>>> Repeat, I understand your words ... but remember that not all the 
>>>> people
>>>> are stupid and do not want to find bug.
>>>> You do not know the skills of the persons on the other side, so my
>>>> advice is to try to understand which kind of person you are 
>>>> contacting.
>>>> It is not so easy ... but it could be important in your work.
>>>
>>> What are you talking about? You ask a question, I reply rapidly with
>>> some ideas to test. You do not want to test these ideas, so the
>>> conclusion is: debug the issue on your own. I do not know any other
>>> answer than the one I gave you.
>>>
>>>
>> Studying the problem it seems that xenomai works fine.
>> The problem maybe is related to not re-entrance of sin and cos function.
>> If I use simple float operation I do not see the problem.
>>
>> I have the same problem using two non realtime task, so I can say that
>> the problem is not related to xenomai.
>
> In order to be sure that the bug is not introduced by Xenomai, you 
> should disable CONFIG_XENOMAI, CONFIG_IPIPE, and in fact, even try the 
> unpatched kernel. And again: you can use the switchtest tool to test 
> whether FPU is OK (with CONFIG_XENOMAI), and if switchtest fails after 
> some time, we have tools to make debugging much easier.
>
> Also note that the 3.0 kernel was released more than 3 years ago, so 
> it is entirely possible that mainline bugs have been fixed since then, 
> both on Linux side, and on I-pipe side, which is the reason I asked 
> you to test a more recent kernel.
>
I'm sorry ... all works correctly, also with hardware floating point. It 
was all my fault.
Paolo

Re: [Xenomai] arm imx6 and hardware FPU [SOLVED]

[Paolo Minazzi]

Il 18/04/2014 11.00, Tom Evans ha scritto:
>> I'm sorry ... all works correctly, also with hardware floating point. It
>> was all my fault.
>> Paolo
>
> Please post the solution in case someone else has the same problem.
>
> Did you forget CONFIG_VFP in the kernel configuration, or is there 
> something different for i.MX6?
>
> The Kernel has to be told about the FPU so it can swap out all the FPU 
> registers during a context swap.
>
> We have a product with an FPU we configure without kernel support, and 
> then only compile ONE program with hardware FP as the FPU context 
> switch time would slow the device down otherwise.
>
> Tom Evans
>
>
The bug was is my test. All alarms was dummy.
In my first email to mailing list I wrote the important points of my 
configuration. Thay were correct.
There are no problem of reentrance of math function.
All compiled with a linaro toolchain hf (hardware floating).
Repeat, all was my buggy test.