mpic discovery on JS20

[Benjamin Herrenschmidt]

On Thu, 2006-07-20 at 19:16 -0400, Amos Waterland wrote:
> Current Linus and Paulus trees do this on JS20 blades with SLOF:

I need a tarball of /proc/device-tree on these. 

>  Failed to locate the MPIC interrupt controller
>  PID hash table entries: 4096 (order: 12, 32768 bytes)
>  Maple: Found RTC at IO 0x1070
>  cpu 0x0: Vector: 700 (Program Check) at [c00000007ef83ab0]
>      pc: c00000000002e0c8: .mpic_request_ipis+0x34/0xc8
>      lr: c00000000036b484: .smp_mpic_probe+0x3c/0x58
>      sp: c00000007ef83d30
>     msr: 9000000000029032
>    current = 0xc00000000194d610
>    paca    = 0xc00000000038f180
>      pid   = 1, comm = swapper
>  kernel BUG in mpic_request_ipis at arch/powerpc/sysdev/mpic.c:1132!
> 
> Doing a git-bisect produces this:
> 
>  0ebfff1491ef85d41ddf9c633834838be144f69f is first bad commit
>  Author: Benjamin Herrenschmidt <benh at kernel.crashing.org>
>  Date:   Mon Jul 3 21:36:01 2006 +1000
> 
>     [POWERPC] Add new interrupt mapping core and change platforms to use it
>     
>     This adds the new irq remapper core and removes the old one.  Because
>     there are some fundamental conflicts with the old code, like the value
>     of NO_IRQ which I'm now setting to 0 (as per discussions with Linus),
>     etc..., this commit also changes the relevant platform and driver code
>     over to use the new remapper (so as not to cause difficulties later
>     in bisecting).
>     
>     This patch removes the old pre-parsing of the open firmware interrupt
>     tree along with all the bogus assumptions it made to try to renumber
>     interrupts according to the platform. This is all to be handled by the
>     new code now.
>     
>     For the pSeries XICS interrupt controller, a single remapper host is
>     created for the whole machine regardless of how many interrupt
>     presentation and source controllers are found, and it's set to match
>     any device node that isn't a 8259.  That works fine on pSeries and
>     avoids having to deal with some of the complexities of split source
>     controllers vs. presentation controllers in the pSeries device trees.
>     
>     The powerpc i8259 PIC driver now always requests the legacy interrupt
>     range. It also has the feature of being able to match any device node
>     (including NULL) if passed no device node as an input. That will help
>     porting over platforms with broken device-trees like Pegasos who don't
>     have a proper interrupt tree.
>     
>     Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
>     Signed-off-by: Paul Mackerras <paulus at samba.org>
> 
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