ARM946E-S attempt (gdb patches / insight)

Joel Sherrill joel.sherrill at
Tue Aug 12 09:36:24 UTC 2008

Smith, Gene SEA wrote:
> How do you set the compile option to -O0 so it takes effect everywhere
> (building rtems and your app)?
the make/custom file.

FWIW I had to do some analysis on the SPARC and found
-Os much easier to read and ~10% smaller executables.

> -----Original Message-----
> From: rtems-users-bounces at
> [mailto:rtems-users-bounces at] On Behalf Of Joel Sherrill
> Sent: Monday, March 24, 2008 4:24 PM
> To: gds
> Cc: rtems-users at
> Subject: Re: ARM946E-S attempt (gdb patches / insight)
> gds wrote:
>> In my attempt to build an ARM946E-S bsp I hijacked the existing csb337
>> bsp as a starting point. I have built an arm-rtems4.8-insight debugger
>> in addition to the standard gdb. However, I never applied the rtems
>> gdb6.6 patches to the insight 6.6 tree. Are they needed with insight?
>> Anyhow, when running insight debugger I seems that, in "mixed mode", I
>> don't always see the assembly instructions associated with the correct
>> source line. The order seems somewhat random and jumps around when I
>> step. In the attached example you can see that the instructions
>> associated with a c source line are not always sequentially
> increasing.
>> Would that be expected with arm architecture, which I have not worked
>> with before? Would lack of rtems patches affect this?
> It isn't an RTEMS issue.  With optimized code on RISC CPUs,
> the assembly from multiple source lines might be intermixed
> for performance reasons.  I know the PowerPC and SPARC are
> pretty aggressive about this and it can be VERY frustrating.
> Some people compile at -O0 when things to make this phase
> of debugging easier.  But remember, your code may break
> again at -O2 especially in the case of missing volatiles.
>> The code shown in ex.txt is from bspstart.c.
>> -gene
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Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at        On-Line Applications Research
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