[Xenomai-core] [bug-reminder] user/kernel space header deps

[Xenomai-core] [bug-reminder] user/kernel space header deps

[Jan Kiszka]

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Hi,

just to avoid that this issue got lost during the migration to Xenomai:

It's still not possible to compile a C++ POSIX program with CFLAGS
obtained via "xeno-config --posix-ldflags". This is due to the fact that
low-level, C++-incompatible headers get included in that case. Moreover,
the same scenarion works for native skin programs only by chance at the
moment.

On the long term, a clear separation between types, defines, function
prototypes, etc. needed for the user API on the one and for core
compilation on the other side is required.

Jan

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Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Philippe Gerum]

Jan Kiszka wrote:
> Hi,
> 
> just to avoid that this issue got lost during the migration to Xenomai:
> 
> It's still not possible to compile a C++ POSIX program with CFLAGS
> obtained via "xeno-config --posix-ldflags". This is due to the fact that
> low-level, C++-incompatible headers get included in that case. Moreover,
> the same scenarion works for native skin programs only by chance at the
> moment.
> 
> On the long term, a clear separation between types, defines, function
> prototypes, etc. needed for the user API on the one and for core
> compilation on the other side is required.
> 

Without duplicating definitions and ABI information, otherwise this would be an 
absolute nightmare. Suggestions welcome.

-- 

Philippe.

Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Jan Kiszka]

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Philippe Gerum wrote:
> Jan Kiszka wrote:
> 
>> Hi,
>>
>> just to avoid that this issue got lost during the migration to Xenomai:
>>
>> It's still not possible to compile a C++ POSIX program with CFLAGS
>> obtained via "xeno-config --posix-ldflags". This is due to the fact that
>> low-level, C++-incompatible headers get included in that case. Moreover,
>> the same scenarion works for native skin programs only by chance at the
>> moment.
>>
>> On the long term, a clear separation between types, defines, function
>> prototypes, etc. needed for the user API on the one and for core
>> compilation on the other side is required.
>>
> 
> Without duplicating definitions and ABI information, otherwise this
> would be an absolute nightmare. Suggestions welcome.
> 

To pick up this issue again (as it's biting me more and more...):

What precisely prevents us at the moment from removing the
-I<kernel-headers> from all userspace build steps, both Xenomai's own
libraries as well as external rt-applications?

Gilles explained to me that at least asm/atomic.h is used by certain
parts like UVM (or only UVM?), and that including this header directly
from /usr/include fails on Red Hat/Fedora boxes. Are there any further
problems? At least on my SuSE 10 everything still compiles fine
(including UVM) when I remove the kernel headers from XENO_USER_CFLAGS
in configure.in.

Jan

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Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Philippe Gerum]

Jan Kiszka wrote:
> Philippe Gerum wrote:
> 
>>Jan Kiszka wrote:
>>
>>
>>>Hi,
>>>
>>>just to avoid that this issue got lost during the migration to Xenomai:
>>>
>>>It's still not possible to compile a C++ POSIX program with CFLAGS
>>>obtained via "xeno-config --posix-ldflags". This is due to the fact that
>>>low-level, C++-incompatible headers get included in that case. Moreover,
>>>the same scenarion works for native skin programs only by chance at the
>>>moment.
>>>
>>>On the long term, a clear separation between types, defines, function
>>>prototypes, etc. needed for the user API on the one and for core
>>>compilation on the other side is required.
>>>
>>
>>Without duplicating definitions and ABI information, otherwise this
>>would be an absolute nightmare. Suggestions welcome.
>>
> 
> 
> To pick up this issue again (as it's biting me more and more...):
> 
> What precisely prevents us at the moment from removing the
> -I<kernel-headers> from all userspace build steps, both Xenomai's own
> libraries as well as external rt-applications?
> 

Because a few things like asm/atomic.h and linux/bitops.h are wanted from the 
target header base for compiling some bits of user-space stuff. Not pretty, but 
currently needed. This is probably what needs to be fixed, in which case the -I 
directive would become useless in the same move.

> Gilles explained to me that at least asm/atomic.h is used by certain
> parts like UVM (or only UVM?), and that including this header directly
> from /usr/include fails on Red Hat/Fedora boxes. Are there any further
> problems? At least on my SuSE 10 everything still compiles fine
> (including UVM) when I remove the kernel headers from XENO_USER_CFLAGS
> in configure.in.
>

It's not an issue with such inclusion failing/passing, it's just that it would 
be incorrect to include your host distro's headers for that purpose, since what 
we need here is the _target_ stuff. The fact that it works on your box is just 
because 1) your host == your target arch, and 2) your host header base does not 
seem to implement guards preventing the use of kernel headers in user-space 
context. In cross compilation context, such inclusion would simply break the 
build, since it expects the target architecture headers to be used, not the 
host's ones.

> Jan
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> Xenomai-core mailing list
> Xenomai-core@domain.hid
> https://mail.gna.org/listinfo/xenomai-core


-- 

Philippe.

Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Jan Kiszka]

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Philippe Gerum wrote:
> Jan Kiszka wrote:
>
>> Philippe Gerum wrote:
>>
>>> Jan Kiszka wrote:
>>>
>>>
>>>> Hi,
>>>>
>>>> just to avoid that this issue got lost during the migration to Xenomai:
>>>>
>>>> It's still not possible to compile a C++ POSIX program with CFLAGS
>>>> obtained via "xeno-config --posix-ldflags". This is due to the fact
>>>> that
>>>> low-level, C++-incompatible headers get included in that case.
>>>> Moreover,
>>>> the same scenarion works for native skin programs only by chance at the
>>>> moment.
>>>>
>>>> On the long term, a clear separation between types, defines, function
>>>> prototypes, etc. needed for the user API on the one and for core
>>>> compilation on the other side is required.
>>>>
>>>
>>> Without duplicating definitions and ABI information, otherwise this
>>> would be an absolute nightmare. Suggestions welcome.
>>>
>>
>>
>> To pick up this issue again (as it's biting me more and more...):
>>
>> What precisely prevents us at the moment from removing the
>> -I<kernel-headers> from all userspace build steps, both Xenomai's own
>> libraries as well as external rt-applications?
>>
>
> Because a few things like asm/atomic.h and linux/bitops.h are wanted
> from the target header base for compiling some bits of user-space stuff.
> Not pretty, but currently needed. This is probably what needs to be
> fixed, in which case the -I directive would become useless in the same
> move.
>
>> Gilles explained to me that at least asm/atomic.h is used by certain
>> parts like UVM (or only UVM?), and that including this header directly
>> from /usr/include fails on Red Hat/Fedora boxes. Are there any further
>> problems? At least on my SuSE 10 everything still compiles fine
>> (including UVM) when I remove the kernel headers from XENO_USER_CFLAGS
>> in configure.in.
>>
>
> It's not an issue with such inclusion failing/passing, it's just that it
> would be incorrect to include your host distro's headers for that
> purpose, since what we need here is the _target_ stuff. The fact that it
> works on your box is just because 1) your host == your target arch, and
> 2) your host header base does not seem to implement guards preventing
> the use of kernel headers in user-space context. In cross compilation
> context, such inclusion would simply break the build, since it expects
> the target architecture headers to be used, not the host's ones.
>

I see, so the problem is the pre-set link of /usr/include/asm to
/usr/include/asm-i386 in my case.

Anyway, it seems that really few code is involved so that it should be
possible to find either related headers in the standard libc or copy
that few atomic ops to Xenomai's arch-dependent includes.

Jan

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Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Philippe Gerum]

Jan Kiszka wrote:
> Philippe Gerum wrote:
> 
>>Jan Kiszka wrote:
>>
>>
>>>Philippe Gerum wrote:
>>>
>>>
>>>>Jan Kiszka wrote:
>>>>
>>>>
>>>>
>>>>>Hi,
>>>>>
>>>>>just to avoid that this issue got lost during the migration to Xenomai:
>>>>>
>>>>>It's still not possible to compile a C++ POSIX program with CFLAGS
>>>>>obtained via "xeno-config --posix-ldflags". This is due to the fact
>>>>>that
>>>>>low-level, C++-incompatible headers get included in that case.
>>>>>Moreover,
>>>>>the same scenarion works for native skin programs only by chance at the
>>>>>moment.
>>>>>
>>>>>On the long term, a clear separation between types, defines, function
>>>>>prototypes, etc. needed for the user API on the one and for core
>>>>>compilation on the other side is required.
>>>>>
>>>>
>>>>Without duplicating definitions and ABI information, otherwise this
>>>>would be an absolute nightmare. Suggestions welcome.
>>>>
>>>
>>>
>>>To pick up this issue again (as it's biting me more and more...):
>>>
>>>What precisely prevents us at the moment from removing the
>>>-I<kernel-headers> from all userspace build steps, both Xenomai's own
>>>libraries as well as external rt-applications?
>>>
>>
>>Because a few things like asm/atomic.h and linux/bitops.h are wanted
>>from the target header base for compiling some bits of user-space stuff.
>>Not pretty, but currently needed. This is probably what needs to be
>>fixed, in which case the -I directive would become useless in the same
>>move.
>>
>>
>>>Gilles explained to me that at least asm/atomic.h is used by certain
>>>parts like UVM (or only UVM?), and that including this header directly
>>>from /usr/include fails on Red Hat/Fedora boxes. Are there any further
>>>problems? At least on my SuSE 10 everything still compiles fine
>>>(including UVM) when I remove the kernel headers from XENO_USER_CFLAGS
>>>in configure.in.
>>>
>>
>>It's not an issue with such inclusion failing/passing, it's just that it
>>would be incorrect to include your host distro's headers for that
>>purpose, since what we need here is the _target_ stuff. The fact that it
>>works on your box is just because 1) your host == your target arch, and
>>2) your host header base does not seem to implement guards preventing
>>the use of kernel headers in user-space context. In cross compilation
>>context, such inclusion would simply break the build, since it expects
>>the target architecture headers to be used, not the host's ones.
>>
> 
> 
> I see, so the problem is the pre-set link of /usr/include/asm to
> /usr/include/asm-i386 in my case.
> 
> Anyway, it seems that really few code is involved so that it should be
> possible to find either related headers in the standard libc or copy
> that few atomic ops to Xenomai's arch-dependent includes.

Yes, fixing that need is the way to go.

-- 

Philippe.

Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Gilles Chanteperdrix]

Jan Kiszka wrote:
 > Hi,
 > 
 > just to avoid that this issue got lost during the migration to Xenomai:

Before it get lost again, maybe you would like to use our brand-new bug
tracker ?

https://gna.org/bugs/?func=additem&group=xenomai

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Philippe Gerum]

Gilles Chanteperdrix wrote:
> Jan Kiszka wrote:
>  > Hi,
>  > 
>  > just to avoid that this issue got lost during the migration to Xenomai:
> 
> Before it get lost again, maybe you would like to use our brand-new bug
> tracker ?
> 
> https://gna.org/bugs/?func=additem&group=xenomai
> 

Please add the kernel module compilation flags issue you once raised too. This 
one will be solved when the build system is fully refactored though.

-- 

Philippe.

Re: [Xenomai-core] [bug-reminder] user/kernel space header deps

[Jan Kiszka]

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Philippe Gerum wrote:
> Gilles Chanteperdrix wrote:
> 
>> Jan Kiszka wrote:
>>  > Hi,
>>  >  > just to avoid that this issue got lost during the migration to
>> Xenomai:
>>
>> Before it get lost again, maybe you would like to use our brand-new bug
>> tracker ?
>>
>> https://gna.org/bugs/?func=additem&group=xenomai
>>

https://gna.org/bugs/index.php?func=detailitem&item_id=4545

> 
> Please add the kernel module compilation flags issue you once raised
> too. This one will be solved when the build system is fully refactored
> though.
> 

https://gna.org/bugs/index.php?func=detailitem&item_id=4546
(nice to know that this one also causes some of my x86_64 issues)

Jan

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