Sharing Interrupts on a PS/2

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2 total messages Started by Gerry Lachac Fri, 31 May 1991 19:40

#3170

Author: Gerry Lachac
Date: Fri, 31 May 1991 19:40

25 lines
1077 bytes

I have a question concerning the sharing of interrupts by a device
driver on a PS/2.  If I have two drivers that request the same
interrupt using the SetIRQ DevHlp, which ISR (interrupt service
routine) is called first?  For example :

	Driver A calls  SetIRQ(3,ISRa) and later,
	Driver B calls  SetIRQ(3,ISRb)


When an interrupt 3 comes in, does OS/2 call Driver A's ISR first
(since it was the first set) or Driver B's?



-gerry




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Re: Sharing Interrupts on a PS/2

#3174

Author: John Radigan
Date: Tue, 04 Jun 1991 14:08

21 lines
1243 bytes

From article <1991May31.194019.3122@dialogic.com>, by gerry@dialogic.com (Gerry Lachac):
> 	Driver A calls  SetIRQ(3,ISRa) and later,
> 	Driver B calls  SetIRQ(3,ISRb)
> 
> 
> When an interrupt 3 comes in, does OS/2 call Driver A's ISR first
> (since it was the first set) or Driver B's?

I quote from IBM OS/2 Programming Tools and Information 1.2, I/O Subsystems and
Device Support, Volume 1, page 2-20. 

   "POSITION RULE An interrupt handler that shares an interrupt level must
         not depend on its position in the list of handlers for that inter-
         rupt level."

There is no mention of the calling sequence applied by the interrupt manager.


--
John Radigan, Star Gate Technologies, Inc., Solon, Ohio  
Email: jjr@sgtech.uucp		Telephone: (216) 349-1860 x666

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