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From: Terry Lambert <terry@lambert.org>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: slow print problem
Date: Thu, 27 Jun 1996 22:55:54 -0700
Organization: Me
Lines: 33
Message-ID: <31D373EA.36311288@lambert.org>
References: <31C98DE4.41C67EA6@rockwell.cz> <31C9C2C3.675102B3@lambert.org> <4qrnhl$bc@anorak.coverform.lan>
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Brian Somers wrote:
] Terry Lambert (terry@lambert.org) wrote:
] : Your printer port is on IRQ 7, which is the "garbage" interrupt
] : for all unrecognized interrupts, and you have some other device
] : that is generating unexpected interrupts that are going to IRQ 7
] : and flaking out the printer driver; probably a sound card with
] : an open collector microphone connection, or a video card that's
] : spitting vertical retrace interrupts onto IRQ 2.
]
] What's a "garbage" interrupt ? Do you mean "you may have a
] conflicting interrupt" ? Can you elaborate ?
It's the interrupt that the PC hardware latches when the one that
it thought it was supposed to latch is unclaimed by the kernel,
either because you don't have a device driver that owns the
interrupt, or because you do, but it thinks it masked or
disabled, etc..
Basically, any driver on IRQ 7 will get interrupts for all other
unclaimed interrupt traffic which can't be delivered to any other
handler.
IRQ 7 is the garbage interrupt, where the interrupt controller
dumps its garbage.
Your printer driver is there to catch it.
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.