Epiphany port - printf prints wrong values of vars argument list

[Gedare Bloom]

With only a string, printf goes to puts. So it sounds like the printf
with arguments is broken. There is a slew of code hiding underneath
the printf interface, and tiny problems in register ABI and memory
layout easily render printf broken. I would start by modifying hello
world to print a formatted string, so that you isolate from any
problems due to timers / interrupts. You can then step in printf and
see what the register arguments are, and that they correspond to what
you might expect. Stepping through printf is a painful, tedious
exercise, but hopefully you can find where things are going wrong. You
might also try to binary search through the call trace, by generating
the stack trace and then checking along it to see what the function
arguments are, and how they track back to the high-level printf()
call.

-Gedare

On Thu, Dec 4, 2014 at 12:46 PM, Hesham Moustafa
<heshamelmatary at gmail.com> wrote:
> Hi,
>
> I have a problem with getting printf working correctly. printf is
> working totally fine with just one string argument (hello world for
> example), however when printf is passed some variable arguments, it
> totally prints some garbage strings. Printing time function (in
> ticker) is an example for this, even a simple printf("x = %d", x);
> where x is defined before to an arbitrary value, output a wrong value
> for x, although it output the "x =" string right. I made sure that the
> address of x (or time structure content in case of ticker) is not
> overwritten, and from GDB, breaking at this and printing x or
> time->seconds for example gets me the right expected values. I think
> the problem is with var arg list, any ideas?
>
> Thanks,
> Hesham
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