PERFORCE change 94334 for review

[Marcel Moolenaar]

On Mar 31, 2006, at 5:51 AM, John Baldwin wrote:

> On Thursday 30 March 2006 06:48 pm, Marcel Moolenaar wrote:
>> http://perforce.freebsd.org/chv.cgi?CH=94334
>>
>> Change 94334 by marcel at marcel_nfs on 2006/03/30 23:47:36
>>
>> 	Strip-down puc(4):
>> 	o  Remove PUC_PORT_TYPE_UART: we always use uart(4) now, so we
>> 	   can use PUC_PORT_TYPE_COM for that.
>> 	o  Remove PUC_PORT_UART_*: we don't support UART sub-types. All
>> 	   UARTs are standard ns8250 again.
>> 	o  Remove PUC_FLAGS_MEMORY and PUC_FLAGS_ALTRES: we try I/O ports
>> 	   first and if that fails, we try memory.
>> 	o  Remove PUC_FASTINTR: we try setting up a fast handler first,
>> 	   and if that fails we try a MPSAFE one.
>
> Unfortunately that algorithm doesn't work in the case of a shared  
> interrupt
> if puc is the first device to attach.  The other devices then just  
> "lose".

It's the standard algorithm I use. I expect the platform to either
share a fast interrupt handler with a non-fast handler or silently
downgrade my fast handler to a mpsafe one if later events demand
this. All I can indicate in my driver is what I'm capable of. The
MD interrupt code should do what needs to be done based on that
and the surrounding environment and subsequent events. I have no
visibility over and/or knowledge about that and cannot program
for it then.

-- 
  Marcel Moolenaar         USPA: A-39004          marcel at xcllnt.net