[ECOS] printf does not work in user mode on Arm E7T

Jonathan Larmour jifl@eCosCentric.com
Mon Mar 31 16:18:00 GMT 2003

Pierre Habraken wrote:
> I just compiled and ran the test program (sources below) on the E7T
> board, using this time Angel and RDI instead of Redboot: the Arm BL
> instructions (and thus the call to printf) executes perfectly when the
> processor is in user mode. As BL fails to execute when the program is
> run against Redboot, I understand that something in the latter goes
> wrong as regards user mode execution.
> Can someone tell me where I could look in Redboot code in order to
> understand the problem ???

Use "set debug remote 1" in GDB and try and find out if anything is not 
right in the traffic there. After that you should look in hal/common's 
generic-stub.c which is where the GDB packets get read and mostly acted on.

Finally, there's arm/arch's arm_stub.c which contains code to determine 
the next PC on a single step. That's definitely worth a look given your 
problem, although the odd thing is how this works for others, but maybe 
something changed a while back and no-one's noticed yet! I don't have an 
arm target here to test I'm afraid.

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