Re: [Adeos-main] adeos porting

[Philippe Gerum <rpm@xenomai.org>]

On Wed, 2004-08-04 at 15:35, aaron durbin wrote:
> Hi,
> 
> I am planning on porting ADEOS over to m68knommu (ColdFire based)
> architecture.  I have read the porting guidelines, however they are a little
> outdated. Currently I am using the recently released
> adeos-linux-2.6.7-i386-r6c6.patch patch for a basis. I was wondering if
> there was any more recent documentation on the API so I know exactly what
> calls should be performed in entry.S.

This one is pretty much in sync with the latest developments:
http://home.gna.org/adeos/doc/api/globals.html

This said, you cannot infer from that what's needed in entry.S. What you
need to do there is basically intercepting the hw IRQ masking/unmasking
and call the corresponding Adeos routines instead
(__adeos_stall/unstall_root), so that interrupts can go through the
pipeline when caught there too, even if the kernel won't receive them.

> 
> The issue I am running into is that the version 2 core of ColdFire does not
> have user/kernel stack support in hardware.  Therefore in entry.S needs to
> disable interrupts to make the stack switch atomic.  I was wondering if it
> would be sufficient to just stall the pipeline for linux at this point and
> make sure to unstall as apposed to disabling interrupts.
> 

Yes. Be careful with the register trashing though; calling the Adeos
pipeline controls might require a bit of tweaking in entry.S so that you
don't end up with a register mess upon return.

> My plans are to first port over ADEOS then go for RTAI.  The two coupled
> together look very promising, and I am hoping they will work as well for
> ColdFire as it does for x86.  
> 

Do you target the 3.0, 3.1 or fusion (poised to become 4.0) branch?

> Thanks for the help,
> Aaron Durbin 
> 
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-- 

Philippe.