[Bug 1572] New: Autoconf Offset macro help needed

[bugzilla-daemon at rtems.org]

https://www.rtems.org/bugzilla/show_bug.cgi?id=1572

           Summary: Autoconf Offset macro help needed
           Product: RTEMS
           Version: HEAD
          Platform: All
        OS/Version: RTEMS
            Status: NEW
          Severity: normal
          Priority: P3
         Component: build
        AssignedTo: ralf.corsepius at rtems.org
        ReportedBy: joel.sherrill at oarcorp.com
                CC: chrisj at rtems.org


Created an attachment (id=801)
 --> (http://www.rtems.org/bugzilla/attachment.cgi?id=801)
code to probe for size

For SMP support, we need to have a per CPU data structure.  This structure 
has fields like executing, heir, interrupt stack, and dispatch needed for
each CPU core.  This is accepted practice and 

I have this working in a development tree along with the next steps in
SMP support.  I am cleaning up my per CPU patch so it has no SMP references.
It is the first step in SMP support and doesn't have an impact on performance.
Before I submit this patch for review, there is an issue I do not know how to 
address.

The elements of this data structure must be accessed from assembly files. 
We have to know the offset of these elements on a per target basis. Since the
offsets can vary based upon compiler flags and version AND they need to
be constants in the assembly file, this seemed like a good job for autoconf
to generate.

I have attached a tarball of some code that can print the offset of an
element in a test structure.  It works on all 4.11 gcc's I have.

/opt/rtems-4.11/bin/arm-rtems4.11-gcc 4
/opt/rtems-4.11/bin/avr-rtems4.11-gcc 2
/opt/rtems-4.11/bin/bfin-rtems4.11-gcc 4
/opt/rtems-4.11/bin/h8300-rtems4.11-gcc 2
/opt/rtems-4.11/bin/i386-rtems4.11-gcc 4
/opt/rtems-4.11/bin/lm32-rtems4.11-gcc 4
/opt/rtems-4.11/bin/m32c-rtems4.11-gcc 2
/opt/rtems-4.11/bin/m32r-rtems4.11-gcc 4
/opt/rtems-4.11/bin/m68k-rtems4.11-gcc 4
/opt/rtems-4.11/bin/mips-rtems4.11-gcc 4
/opt/rtems-4.11/bin/powerpc-rtems4.11-gcc 4
/opt/rtems-4.11/bin/sh-rtems4.11-gcc 4
/opt/rtems-4.11/bin/sparc64-rtems4.11-gcc 8
/opt/rtems-4.11/bin/sparc-rtems4.11-gcc 4

Please help generate this information.

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