[PATCH 00/16] irqchip: gic: killing gic_arch_extn, slowly

Marc Zyngier marc.zyngier at arm.com
Wed Dec 3 06:59:00 PST 2014

Hi Arnd,

On 03/12/14 14:30, Arnd Bergmann wrote:
> On Tuesday 02 December 2014 16:58:01 Marc Zyngier wrote:
>> - This actively *breaks* existing setups. Once you boot a new kernel
>>   with an old DT, suspend/resume *will* be broken. Old kernels on a
>>   new DT won't even boot! You've been warned. This really outline the
>>   necessity of actually describing the HW in device trees...
> I wonder if we should take this as the trigger to come up with a
> better way of handling incompatible binding changes. The machine_desc
> has a .dt_fixup callback that we could use to modify the DT passed
> from a boot loader and warn about it, but no platform does this
> at the moment.
> From what I can tell, the required change to get an old dtb working
> with a new kernel is to add a particular node and flip a few
> interrupt-parent properties, which seems doable as a quirk if
> people agree that it's a good idea.

That's probably the only way to avoid the breakage introduced by this
kind of changes. A few questions though:
- Where do we stop? Eventually, don't we end-up with a full DT in there?
- When do we retire such fixup? Or do we keep them forever?


Jazz is not dead. It just smells funny...

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