On Wed, 2009-08-05 at 17:51 -0400, Andreas Glatz wrote:
> Hi,
>
> I'm running xenomai-2.4.8, Linux-2.6.26 on a MPC8360 PowerPC.
>
> I enabled nucleus debugging and found out that tasks sometimes
> switch to secondary mode due to data alignment exceptions (#1536 ==
> 0x600):
>
> <snip>
> Xenomai: Switching bgndT30_3 to secondary mode after exception #1536
> from user-space at 0x101013f4 (pid 3191)
> Xenomai: Switching bgndT30_3 to secondary mode after exception #1536
> from user-space at 0x101013f4 (pid 3191)
> ...
> </snip>
>
> I know that we get those exceptions because we pass the -fpack-struct
> option to gcc and some data in structures are misaligned. It would
> be quite a lot of work to go through the code to change it so that
> we don't have to pass the -fpack-struct option.
>
> Is there a way to execute the exception handler from primary mode
> to prevent the tasks to switch to secondary mode?
I have absolutely no freaking idea whether the following patch will
work, but you are welcome to feel lucky:
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 701fe3b..3efe546 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -917,7 +917,8 @@ void alignment_exception(struct pt_regs *regs)
{
int sig, code, fixed = 0;
- if (ipipe_trap_notify(IPIPE_TRAP_ALIGNMENT,regs))
+ if (test_bit(IPIPE_NOSTACK_FLAG, &ipipe_this_cpudom_var(status)) &&
+ ipipe_trap_notify(IPIPE_TRAP_ALIGNMENT, regs))
return;
/* we don't implement logging of alignment exceptions */
@@ -930,6 +931,10 @@ void alignment_exception(struct pt_regs *regs)
return;
}
+ if (!ipipe_root_domain_p &&
+ ipipe_trap_notify(IPIPE_TRAP_ALIGNMENT, regs))
+ return;
+
/* Operand address was bad */
if (fixed == -EFAULT) {
sig = SIGSEGV;
>
> Best regards,
> Andreas
>
>
> _______________________________________________
> Xenomai-help mailing list
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--
Philippe.
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