[PATCH] Re: Linkstation Mini and __machine_arch_type problem, not booting since 3.8

[Benjamin Cama]

Hi Russell,

Le 2015-06-19 15:13, Russell King - ARM Linux a écrit :
> On Fri, Jun 19, 2015 at 02:16:34PM +0200, Benjamin Cama wrote:
>> Le vendredi 19 juin 2015 à 10:13 +0100, Marc Zyngier a écrit :
>> > On 19/06/15 02:38, Benjamin Cama wrote:
>> > > Le jeudi 18 juin 2015 à 08:52 +0100, Marc Zyngier a écrit :
>> > >> Unfortunately, this is the wrong thing to do. IRQ0 is invalid, 
>> has been
>> > >> for a very long time, and actually represents the lack of 
>> interrupt.
>> > >
>> > > OK, sorry for the mistake, I didn't know. Shouldn't the IRQ
>> > > initialization routine check this and warn the user that it may 
>> cause
>> > > problems? “Silently” making IRQ0 forbidden doesn't help for the
>> > > platforms that are not fixed yet.
>> >
>> > Well, this is hardly a new rule. It has been like this for quite a 
>> long
>> > time: http://yarchive.net/comp/linux/zero.html
>> >
>> > As for the checking and warning, this is on a very hot path, for 
>> an
>> > error case that really shouldn't occur.
>>
>> I was not talking about the irq handler, but the irq initialization
>> routine (on orion5x, orion_irq_init calls irq_alloc_generic_chip 
>> with
>> 0), which takes the starting irq number and may warn when it is zero
>> (well, it may also start allocating at zero but never use it, so 
>> this
>> may not be a totally correct assumption, but I think this comes 
>> close,
>> and it's just a warning).
>
> It needs fixing nevertheless - arguments along the lines of "this 
> used
> to work" don't work for this topic.
>
> The simple answer is to adjust the initialisation to bump the IRQ
> numbers up by one, and them adjust the interrupt numbers in
> arch/arm/mach-whatever/include/asm/irqs.h also up by one.  That's
> far easier to do than spending ages trying to argue against the
> "IRQ0 is not valid" issue, only to ultimately get nowhere, and end
> up with that as the only way forward anyway.

Do not misunderstand me: I am not at all for keeping the situation like 
this!
What I ask is just for users to be notified of this new requirement: 
for my
case, my board simply couldn't boot anymore, without any explanation. 
If there
was a message along the lines “You are setting up IRQs starting from 0, 
which
is not supported by the kernel anymore” just before crashing, maybe it 
would
help debugging the issue.

I could try to write a patch for it, but I was first wondering if this 
is a
good idea or not.

Regards,
--
benjamin