Re: how to tell Linux *not* to share IRQs ?

[Per Jessen]

On Wed, 8 Aug 2001 12:13:40 -0500 (EST), Mark H. Wood wrote:

>On Wed, 8 Aug 2001, Andrew McNamara wrote:
>[snippage]
>> The problem is largely historical - each interrupt traditionally had a
>> physically line associated with it, and lines on your backplane were a
>> limited resource.
>>
>> If you were to do it again these days, you might have some sort of
>> shared serial bus, so devices could give detailed data to the cpu
>> (not only to uniquely identify the interrupting device, but also
>> identify sub-devices - say a USB peripheral).
>
>See for example "vectored interrupts" on the PDP10.  The device driver
>tells the device where the driver's ISR is, and when the device
>interrupts, it puts that address on the bus.  The interrupt logic jumps
>directly to the ISR, which "knows" it is the only driver that would be
>interested in this interrupt.  (You could set up a jump table if you
>wanted to, so that each device of the same type could identify itself
>uniquely, but that typically wasn't a big problem in '10 installations
>where multiples were most likely in a PDP11 on the other side of a DTE20,
>or Massbus devices on a single RH20.)
>
>Apparently this idea is now so old that it is new. :-)

Yeah - I believe the same was possible on the Z80 - though I'd have to 
go read the manual to be certain.

regards,
Per Jessen, Zurich

Windows 2001: "I'm sorry Dave ...  I'm afraid I can't do that."

regards,
Per Jessen, Zurich
http://www.enidan.com - home of the J1 serial console.

Windows 2001: "I'm sorry Dave ...  I'm afraid I can't do that."