Finding include directories in the sysroot

Finding include directories in the sysroot

[Stephen Kelly]

Hi there,

I have a rootfs which has Qt installed in /usr. So for example, qobject.h
exists at /usr/include/QtCore/qobject.h.

My rootfs is at ~/rpi/rasp-pi-rootfs.

I invoke

  arm-linux-gnueabihf-g++-4.7 --sysroot=/home/stephen/rpi/rasp-pi-rootfs \
   -I/usr/include/QtCore  -v -c myfile.cpp

and I see this:

  ignoring nonexistent directory "/usr/include/QtCore"
  #include "..." search starts here:
  #include <...> search starts here:
  /usr/lib/gcc-cross/arm-linux-gnueabihf/4.7/include
  /usr/lib/gcc-cross/arm-linux-gnueabihf/4.7/include-fixed
  /usr/lib/gcc-cross/arm-linux-gnueabihf/4.7/../../../../arm-linux-
gnueabihf/include
  /home/stephen/rpi/rasp-pi-rootfs/usr/include/arm-linux-gnueabihf
  /home/stephen/rpi/rasp-pi-rootfs/usr/include
  End of search list.


So, it's not finding /usr/include/QtCore in my host root file system, and
it
is not looking in the sysroot I passed, as I expected. I also tried using
the -isysroot option, with a similar result.

Is my expectation incorrect? What can I really expect from the sysroot
option?

My goal is implementing proper sysroot handling for the cmake buildsystem
tool, so I need to understand how it is intended to work and what can be
expected of it.

Thanks,

Steve.


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Re: Finding include directories in the sysroot

[Yann E. MORIN]

Stephen, All,

On 2013-05-20 20:38 +0200, Stephen Kelly spake thusly:
> I have a rootfs which has Qt installed in /usr. So for example, qobject.h
> exists at /usr/include/QtCore/qobject.h.
> 
> My rootfs is at ~/rpi/rasp-pi-rootfs.
> 
> I invoke
> 
>  arm-linux-gnueabihf-g++-4.7 --sysroot=/home/stephen/rpi/rasp-pi-rootfs \
>   -I/usr/include/QtCore  -v -c myfile.cpp

From the gcc manpage for -I :
    -I dir
        Add the directory dir to the list of directories to be searched
        for header files.  Directories named by -I are searched before
        the standard system include directories.  If the directory dir
        is a standard system include directory, the option is ignored
        to ensure that the default search order for system directories
        and the special treatment of system headers are not defeated.
        If dir begins with "=", then the "=" will be replaced by the
        sysroot prefix; see --sysroot and -isysroot.

So, absolute paths are just taken as-is. If you want it to be relative
to the sysroot, you have to prepend a '=' sign, as thus (untested):

  arm-linux-gnueabihf-g++-4.7 --sysroot=/home/stephen/rpi/rasp-pi-rootfs \
   -I=/usr/include/QtCore  -v -c myfile.cpp

Regards,
Yann E. MORIN.

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