[Xenomai-core] Re: [Adeos-main] Re: adeos-ipipe-2.6.18-ppc-1.4-00.patch, first version

[Philippe Gerum <rpm@xenomai.org>]

On Sat, 2006-09-30 at 11:23 +0200, Wolfgang Grandegger wrote:
> Hi Philippe,
> 
> Philippe Gerum wrote:
> > On Sun, 2006-09-24 at 22:55 +0200, Wolfgang Grandegger wrote:
> >> Hi Philippe,
> >>
> >> attached you will find a first version of the PPC ADEOS-IPipe patch for 
> >> Linux 2.6.18 (from kernel.org) for review. I have also included a 
> >> commented log file with more information on the porting of 
> >> adeos-ipipe-2.6.14-ppc-1.4-00 to Linux 2.6.18. It works with a recent 
> >> version of Xenomai.
> >>
> > 
> > Thanks, at first sight, this looks good. I don't see any obvious problem
> > in the tracer code either. Anyway, I will play with it asap.
> > 
> >> The patch currently only supports devices in the "arch/ppc" tree with 
> >> the option "CONFIG_PPC_MERGE" not set. Porting the "arch/powerpc" tree 
> >> requires further effort and I need a test system as well. Puh, let's 
> >> hope that the merge ppc -> powerpc will be completed soon.
> >>
> >> The idle loop is not yet working for 6xx and I have disabled it for
> >> this reason (check arch/powerpc/kernel/idle.c). It needs further
> >> debugging. I hope to find more time beginning of October.
> > 
> > Ok, thanks. Btw, returning from NAP on 6xx is done through an exception,
> > right? If so, maybe we have a problem with this particular
> > exception/interrupt branching directly to transfer_to_handler_full (i.e.
> > the vanilla way) without being known from the Adeos pipeline, albeit it
> > should? (red blinking warning: this is just a wild guess).
> 
> Attached is a revised patch including a fix for remaining problem in the 
> 6xx idle loop mentioned above. The bug was here (diff to old patch):
> 
> -+++ linux-2.6.18/arch/ppc/kernel/entry.S
> ++++ linux-2.6.18/arch/ppc/kernel/entry.S
>   @@ -132,8 +132,23 @@
>             * check for stack overflow
>             */
> @@ -78,9 +73,9 @@
>   +      &current->thread_info to &current->thread, which is coarser
>   +      than the vanilla implementation, but likely sensitive enough
>   +      to catch overflows soon enough though.*/
> -+      addi    r11,r9,THREAD
> ++      addi    r12,r9,THREAD
>   +      cmplw   0,r1,r9
> -+      cmplw   1,r1,r11
> ++      cmplw   1,r1,r12
>   +      crand   1,1,4
>   +      bgt-    stack_ovf               /* if r9 < r1 < r9+THREAD */
>   +#else /* CONFIG_IPIPE */
> 
> I accidentally used r11 for the above logic, which is in fact used in 
> power_save_6xx_restore:

Gasp. Hopefully, one day, we will not have to work around the dual stack
model anymore, because even Xenomai kernel threads will be based on
regular Linux TCBs. Thanks for the patch.

-- 
Philippe.