Re: [Xenomai-core] [PATCH] Shared irqs v.6

[Jan Kiszka <jan.kiszka@domain.hid>]

Dmitry Adamushko wrote:
> On 31/01/06, Jan Kiszka <jan.kiszka@domain.hid> wrote:
>> Dmitry Adamushko wrote:
>>> Hi,
>>>
>>> the previous version contained an ugly bug, namely the misuse of the
>>> test_and_set/clear_bit interface
>>> that led to a broken system from time to time.
>>>
>> What about the ISA/edge-triggered stuff? :D
>>
>> My problem is that we cannot test here on real hardware because all our
>> shared IRQs reside on PC104 cards.
> 
> 
> Could you provide me with some real piece of such code as an example?

May I remind you of the link to the linux kernel's 8250 driver I gave?
Or what do you mean with real code? xeno_16550A would become such a user
ideally only by adding one or two IRQ-registration flags.

> 
> Anyway, design-wise, it's about introducing a separate xnintr_handler() for
> such a special case to avoid getting a mixture with the rest of "sane" code.

Yep, I would vote for this approach as well.

> I mean that the support of shared interrupts for ISA boards (edge-triggered
> stuff) is a kind of emulation to overcome the shortcommings of the initial
> design on the hardware level. The hardware was just not supposed to support
> shared interrupt channels. So, let's keep it a bit aside from another code
> :o)

Unfortunately, this crappy hardware is still quite common in the
embedded domain.

> 
> xnintr_attach() will check for a special flag like XN_ISR_ISASHARED and
> attach e.g. xnintr_isairq_handler() instead of xnintr_irq_handler().
> 
> I'll post an extension to the rt_intr_create(..., const char *name, ...)
> tomorrow - made but not tested yet -
> 
> as well as the /proc support.
> 

This should be easy... Great!

Jan