Removal of arm OABI support possible?

Removal of arm OABI support possible?

[Florian Bezdeka]

Hi all,

Clara is currently trying to enable compat support for arm64. That will
allow us to run arm(hf) applications on arm64 kernels like we do it for
i386 applications on x86_64 kernels.

We fixed the Xenomai arm specific register layout in a way that is
compatible to arm64. That looks promising as the testsuite (smokey) can
already be executed successfully in such a compat environment.

The changes we made affect the EABI only and we left the OABI interface
untouched and expect it to be broken right now. We can't really test it
here...

Is there still the need for OABI support in Xenomai? OABI is marked as
obsolete since gcc > 4.6.4 (~2013) and Debian stopped shipping oabi
toolchains long time ago. Would it be accepted if we simply drop the
OABI support of Xenomai?

Best regards,
Florian

Re: Removal of arm OABI support possible?

[Jan Kiszka]

On 07.08.23 15:29, Florian Bezdeka wrote:
> Hi all,
> 
> Clara is currently trying to enable compat support for arm64. That will
> allow us to run arm(hf) applications on arm64 kernels like we do it for
> i386 applications on x86_64 kernels.
> 
> We fixed the Xenomai arm specific register layout in a way that is
> compatible to arm64. That looks promising as the testsuite (smokey) can
> already be executed successfully in such a compat environment.
> 
> The changes we made affect the EABI only and we left the OABI interface
> untouched and expect it to be broken right now. We can't really test it
> here...
> 
> Is there still the need for OABI support in Xenomai? OABI is marked as
> obsolete since gcc > 4.6.4 (~2013) and Debian stopped shipping oabi
> toolchains long time ago. Would it be accepted if we simply drop the
> OABI support of Xenomai?

From Xenomai 3 perspective, it would be fine to finally drop that with
the 3.3 release - patch(es) welcome.

Not sure, though, how the situation of Xenomai 4 / EVL is in this regard
- Philippe?

Jan

-- 
Siemens AG, Technology
Linux Expert Center

Re: Removal of arm OABI support possible?

[Florian Bezdeka]

On Tue, 2023-08-08 at 14:30 +0200, Jan Kiszka wrote:
> On 07.08.23 15:29, Florian Bezdeka wrote:
> > Hi all,
> > 
> > Clara is currently trying to enable compat support for arm64. That will
> > allow us to run arm(hf) applications on arm64 kernels like we do it for
> > i386 applications on x86_64 kernels.
> > 
> > We fixed the Xenomai arm specific register layout in a way that is
> > compatible to arm64. That looks promising as the testsuite (smokey) can
> > already be executed successfully in such a compat environment.
> > 
> > The changes we made affect the EABI only and we left the OABI interface
> > untouched and expect it to be broken right now. We can't really test it
> > here...
> > 
> > Is there still the need for OABI support in Xenomai? OABI is marked as
> > obsolete since gcc > 4.6.4 (~2013) and Debian stopped shipping oabi
> > toolchains long time ago. Would it be accepted if we simply drop the
> > OABI support of Xenomai?
> 
> From Xenomai 3 perspective, it would be fine to finally drop that with
> the 3.3 release - patch(es) welcome.
> 
> Not sure, though, how the situation of Xenomai 4 / EVL is in this regard
> - Philippe?
> 

According to [1] evl is supporting EABI only.

[1] https://source.denx.de/Xenomai/xenomai4/libevl/-/blob/master/lib/arch/arm/include/asm/evl/syscall.h#L26

> Jan
> 

Re: Removal of arm OABI support possible?

[Philippe Gerum]

Jan Kiszka <jan.kiszka@siemens.com> writes:

> On 07.08.23 15:29, Florian Bezdeka wrote:
>> Hi all,
>> 
>> Clara is currently trying to enable compat support for arm64. That will
>> allow us to run arm(hf) applications on arm64 kernels like we do it for
>> i386 applications on x86_64 kernels.
>> 
>> We fixed the Xenomai arm specific register layout in a way that is
>> compatible to arm64. That looks promising as the testsuite (smokey) can
>> already be executed successfully in such a compat environment.
>> 
>> The changes we made affect the EABI only and we left the OABI interface
>> untouched and expect it to be broken right now. We can't really test it
>> here...
>> 
>> Is there still the need for OABI support in Xenomai? OABI is marked as
>> obsolete since gcc > 4.6.4 (~2013) and Debian stopped shipping oabi
>> toolchains long time ago. Would it be accepted if we simply drop the
>> OABI support of Xenomai?
>
> From Xenomai 3 perspective, it would be fine to finally drop that with
> the 3.3 release - patch(es) welcome.
>
> Not sure, though, how the situation of Xenomai 4 / EVL is in this regard
> - Philippe?
>

Having support for OABI was not even considered wrt neither EVL nor
Dovetail (would require specific syscall handling which is not there),
so it is safe to drop it entirely from any current Xenomai 3 codebase.

-- 
Philippe.