[oe] linux-libc-headers-native, gcc-cross issue

[Frans Meulenbroeks]

2010/6/21 Khem Raj <raj.khem at gmail.com>:
> On Sun, Jun 20, 2010 at 1:51 PM, Frans Meulenbroeks
> <fransmeulenbroeks at gmail.com> wrote:
>> Dear all,
>>
>> After the introduction of linux-libc-headers-native I've bumped into
>> the following issue.
>> linux-libc-headers-native installs unistd.h in sysroots
>> This causes other recipes to pick up the x86 files instead of the target ones.
>> I've seen this happen for both unistd.h and sigcontext.h
>>
>> One of the recipes suffering from this is gcc-cross (for some architectures).
>> Reason is that files are compiled with
>> -I/home/frans/oe/tmp_angstrom/sysroots/i686-linux/usr/include whereas
>> the target specific includes are added with -isystem.
>> This causes the -I to win.
>
> right. gcc-cross is a special case where its not building purely cross
> binaries but
> also making libraries and objects that will run on the target. This
> problem probaly
> is seen when building startup objects  (crt*.o). This path is added by
> gcc build
> machinery as a path where it finds gmp headers. I suspect that gcc build should
> not be passing this in the incudes when building target stuff.
>
> I think with sysroot using -isystem<target_headers> should not be needed.

It is not the -isystem that is the problem. as stated above there is
an explicit -I to sysroots/i686-linux that is causing the problem.
This dir used to be unpopulated (or maybe even non-existing), butwith
linux-libc-headers-native it became populated and as it got precedence
the dir wins.
I have no idea how to remove the -I dir (and also no idea if it is ok).

The problem only occurs in .../gcc/config/${ARCH}/
typical issue where this happens is linux_unwind.h This includes
<signal.h> to get <sigcontext.h> and eventually the typedef for
sigcontext.
However sigcontext is of course archtecture specific so if one picks
up the wrong signal.h it does not work.

The unistd.h problem is probably specific for the nios2 variant, in
which an additional system call is defined, which of course is not
present in the x86 unistd.h

Frans

>
>
>>
>> In the past sysroots/i686-linux/usr/include was empty, but with
>> linux-libc-headers-native it gets populated causing the files in there
>> to be used instead of the ones in the target ones.
>> By setting linux-libc-headers-native to ASSUME-PROVIDED and cleaning
>> and rebuilding TMPDIR I was able to avoid the problem.
>
> yeah this masked the problem as it has been masked till now.
>
>>
>> However, I think this needs a more structural solution.
>> Suggestions are appreciated.
>
> We should explore if passing this isystem in CFLAGS is needed at all.
> if not then we should remove it.
>
>>
>> Frans.
>>
>> PS: it might also be that other files suffer from this, but until now
>> I only had problems with gcc-cross
>
> could be but I doubt.
>
>>
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