[Cbe-oss-dev] Refactored cell powerpc oprofile patch

[Michael Ellerman]

On Mon, 2008-03-03 at 14:42 -0800, Carl Love wrote:
> On Tue, 2008-03-04 at 09:18 +1100, Michael Ellerman wrote:
> > On Mon, 2008-03-03 at 09:32 -0800, Carl Love wrote:
> > > At this point, the only issue I see with PS3 support using the existing
> > > CELL code is the FW calls.  The CELL code makes FW calls to setup the
> > > debug bus and do SPU cycle based profiling.  We started the process
> > > within IBM to get approval to share the FW code with Sony and Toshiba so
> > > that all three platforms can share the same FW interface.  This will
> > > eliminate adding any kernel support to access the debug bus registers.
> > > The debug bus setup register address will probably change with the next
> > > version of the HW.  Hence it is necessary to hide that info from the
> > > kernel in the HW specific firmware.
> > 
> > Slightly OT, but this is not entirely true. If it's simply a register
> > address that will change then it'd probably be easier to just put the
> > address in a device-tree property and have linux use that.
> 
> We are actually talking about something on the order of about 20 to 30
> register addresses here.  

Sure, that's still entirely feasible. We have properties with hundreds
of values on some machines.

> Not familiar with the device-tree stuff but OK, sounds like that might
> be an option.  

It's basically just a standard format for firmware to communicate values
to the kernel, and it happens to be a tree structure. Try
'find /proc/device-tree' on any power box to have a look at it.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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