[U-Boot-Users] PPC: problem with syscalls

Pierre AUBERT p.aubert at staubli.com
Thu Nov 28 13:39:53 CET 2002

Hello everybody,

I've a problem with examples/timer.c. I've tried to launch it on my
mpc860t board, if I start the timer and if I
press a key after one or more interrupts occured, the u-boot crashes.
The problem is that an interrupt handler
uses a system call (mon_printf) while the main loop is inside a system
call (mon_getc). During a system call,
the LR and SRRx are saved at a fixed location (0xcf4, 0xcf8 and 0xcfc)
then the return address of the mon_printf
in the main loop is overridden by the return address of the mon_getc in
the interrupt handler. To avoid this problem,
I think that we need to use a stack to store the return addresses (and
the SRRx) of the system calls.

What's your opinion ?

Best regards

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