kern/60050: Toshiba/3Com 3CXM056-BNW: Open Causes Interupt storm/lock

[M. Warner Losh]

The following reply was made to PR kern/60050; it has been noted by GNATS.

From: "M. Warner Losh" <imp at bsdimp.com>
To: jhb at FreeBSD.org
Cc: freebsd-gnats-submit at FreeBSD.org, ler at lerctr.org
Subject: Re: kern/60050: Toshiba/3Com 3CXM056-BNW: Open Causes Interupt
 storm/lock
Date: Mon, 15 Dec 2003 11:09:56 -0700 (MST)

 In message: <200312151300.52685.jhb at FreeBSD.org>
             John Baldwin <jhb at FreeBSD.org> writes:
 : This sounds like another reported problem that may be related to PCCard 
 : devices needing to use an ISA interrupt rather than a PCI one.  The cbb 
 : device is assigned a PCI interrupt and card devices use that PCI interrupt.
 : Windows seems to use an ISA interrupt different from the PCI interrupt in at 
 : least some cases.
 
 Yes.  Using ISA interrupts isn't easy or possible in NEWCARD without a
 lot of rework (unless the bridge is an ISA device).  I'm not convinced
 that this rework would be fruitful.  PC Cards never need to use ISA
 interrupts, but sometimes their drivers do.  PC Cards are agnostic
 about how the interrupt is delivered by the bridge to higher layers.
 CardBus cards always use PCI interrupts only.
 
 Windows uses ISA interrupts because older windows drivers need that to
 happen.  Some windows drivers cannot tolerate being shared at all,
 hence the need.  Even in Windows, however, this is being phased out.
 Only some bridge chipsets support the ISA signaling of some kinds of
 interrupts (the csc ones, or card status change).  Windows also seems
 to have some way of knowing when the cbb bridge is connected to the
 south bridge and ISA interrupts are even possible.  With Add-in pci
 cards, you cannot use ISA interrupts (well, there are a few weird
 add-in cards that are a combination PCI/ISA card for the IRQ lines,
 but those are the exception and very rare).
 
 Warner