printf does not work in user mode on Arm E7T

[Pierre Habraken]

Hello,

For demonstration purpose, I have inserted printf calls in a program
running on an Arm Evaluator 7T (controlled by gdb as a remote target).
The program is linked against newlib libc but and it uses redboot
syscalls (redboot.specs).
Some parts of the program runs in svc mode (cpsr = 0x13), other parts
run in usr mode (cpsr = 0x10), each mode using its own stack.
When printf is called with the processor being in svc mode, the
corresponding output is displayed in the gdb console and the program
continues then with its execution.
When printf is called with the processor being in usr mode, nothing is
displayed in the gdb console and the program hangs or raises a BUS
ERROR.
Could someone explain me what printf would not work in user mode ?

Thanks in advance for any help.

Pierre
-- 
________________________________________________________________________
Pierre HABRAKEN - mailto:Pierre.Habraken@imag.fr
Tél: 04 76 82 72 83 - Fax: 04 76 82 72 87
IMAG-LSR BP72 38402 SAINT MARTIN D'HERES Cedex
________________________________________________________________________