Subject: Re: powerpc allmodconfig build broken due to commit 15863ff3b (powerpc: Make chip-id information available to userspace)

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 11 Sep 2013 08:02:49 +1000

On Mon, 2013-09-09 at 16:55 -0700, Asai Thambi S P wrote:
> On 09/08/2013 5:28 PM, Guenter Roeck wrote:
> > Hi all,
> >
> > powerpc allmodconfig build on the latest upstream kernel results in:
> >
> > ERROR: ".cpu_to_chip_id" [drivers/block/mtip32xx/mtip32xx.ko] undefined!
> >
> > This is due to commit 15863ff3b (powerpc: Make chip-id information 
> > available to userspace).
> > Not surprising, as cpu_to_chip_id() is not exported.
> >
> Apart from the above error, I have a concern on the patch, purely based on the commit message.
> (to be honest, I am not familiar with the ppc architecture)
> 
> Commit message of 15863ff3b has the following text.
> 
> ******************
> So far "/sys/devices/system/cpu/cpuX/topology/physical_package_id"
> was always default (-1) on ppc64 architecture.
> 
> Now, some systems have an ibm,chip-id property in the cpu nodes in
> the device tree. On these systems, we now use this information to
> display physical_package_id
> ******************
> 
> Shouldn't the new definition of "topology_physical_package_id" apply only to those systems supporting ibm,chip-id property?

There should be no negative side effect (appart from the missing
EXPORT_SYMBOL of course). If the property is not found in the
device-tree, the new function returns -1, so it should work fine on all
systems.

Cheers,
Ben.

> 
> > Reverting this commit fixes the problem. Any good idea how to fix it 
> > for real ?
> >
> > Guenter
> > -- 
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