Changing compilation options for BSP building

[Jiri Gaisler]

The 4.6.5 version on the ftp is not complete, I think Joel
removed a small part of our original patch. You can download
our version of 4.6.5 from the link below which work correctly.

Jiri.

ftp://gaisler.com/gaisler.com/rcc/src/rtems-4.6.5-1.0.11.tar.gz


John Pickwick wrote:
> Thanks Bruce,
> it now works fine.
> 
> My assumptions were right : the default setting in RTEMS 4.6.5 implies a 
> leon2 bsp compiled with the -msoft-float that seems to remove the 
> associated FPU context management in the routines that deal with threads.
> 
> After your suggested change and the recompilation of the bsp it works.
> 
> I understand Jiri's remark about a non-FPU leon2 and gcc implicit use of 
> float registers but I just can't see how it could work with a true 
> hardware fpu sparc without removing this flag.
> 
> Thanks to all,
> John
> 
> ----- Original Message ----- From: "Bruce Robinson" <brucer at pmccorp.com>
> To: <rtems-users at rtems.com>
> Cc: "John Pickwick" <john.pickwick at free.fr>
> Sent: Tuesday, February 07, 2006 11:26 PM
> Subject: Re: Changing compilation options for BSP building
> 
> 
>> Hi John,
>>
>> I think the answer to your original question is that you need to edit 
>> the line :
>>
>> CPU_CFLAGS = -mcpu=cypress -msoft-float
>>
>> in the make/custom/leon2.cfg file.
>>
>> Best Regards,
>> Bruce
>>
>> At 12:41 PM 2/7/2006, you wrote:
>>
>>> Thanks for your quick answer Jiri but I intend to try this because I 
>>> have the following problem :
>>> * I've got an application with several tasks and just one floating 
>>> point task, I am targeting the AT697 from ATMEL that has a hardware FPU,
>>> * of course, I created the FP task with FP attribute,
>>> * when RTEMS switches to this task it does not restore the EF bit in 
>>> PSR which implies an "FP disabled" trap on the first floating point 
>>> instruction,
>>> * looking carefully at this problem under gdb I noticed that there 
>>> was no fp_context pointer field in the thread structure associated 
>>> with this task (this pointer is used to manage the fp_context in 
>>> threadloadenv.c for example). So I assumed that there was something 
>>> wrong in my bsp compilation.
>>>
>>> Therefore I found in thread.h that the fp_context field was 
>>> enable/disable by CPU_HARDWARE_FP define which in turn is 
>>> conditionned by SPARC_HAS_FPU define (in cpu.h) that is set or unset 
>>> by _SOFT_FLOAT definition (in sparc.h). In cpu.h the
>>> CPU_SOFTWARE_FP  is also set to FALSE.
>>>
>>> As a consequence :
>>> -msoft-float option
>>>    implies (assumption based on comments in sparc.h)
>>> _SOFT_FLOAT in sparc.h
>>>    implies
>>> SPARC_HAS_FPU == 0 in sparc.h
>>>    implies
>>> CPU_HARDWARE_FP == FALSE in cpu.h
>>> + CPU_SOFTWARE_FP set to FALSE in cpu.h
>>>    which implies a disabled FP management in threadloadenv.c that is 
>>> part of the bsp.
>>>
>>> Can you see what's wrong in my approach ?
>>>
>>> John.
>>>
>>>
>>>
>>> ----- Original Message ----- From: "Jiri Gaisler" <jiri at gaisler.com>
>>> To: "RTEMS Users Mailing List" <rtems-users at rtems.com>
>>> Sent: Tuesday, February 07, 2006 7:57 PM
>>> Subject: Re: Changing compilation options for BSP building
>>>
>>>
>>>>
>>>> I would not recommend to remove the -msoft-float flag from
>>>> CPU_FLAGS. There is not floating point operations done in
>>>> the RTEMS kernel, hence you do not need to generate FPU
>>>> instructions. If you remove the -msoft-float option, newer
>>>> versions of gcc will use FPU registers for certain integer
>>>> operations (!) and the kernel will not run on processors
>>>> without an FPU. Hence, you do not gain anything by removing
>>>> -msoft-float, except the opportunity of crashing on non-FPU
>>>> LEON hardware.
>>>>
>>>> Jiri.
>>>>
>>>>
>>>> John Pickwick wrote:
>>>>
>>>>> Hi to all,
>>>>>
>>>>> What should I do to change the compilation options used during my bsp
>>>>> buid ?
>>>>> I use the LEON2 / RTEMS 4.6.5 BSP and I'd like to replace the 
>>>>> "CPU_FLAGS
>>>>> = -mcpu=cypress -msoft-float" option used during the compilation to
>>>>> suppress the soft-float setting.
>>>>>
>>>>> I tried to set CC_FLAGS_TARGET or CPU_FLAGS directly on my configure
>>>>> command line but it does not work (failed with an 'invalid build 
>>>>> alias'
>>>>> error).
>>>>>
>>>>> Thanks for help,
>>>>> John.
>>>>> .
>>>
>>>
>>>
>>
>>
> 
> .
>