Date: Tue, 25 Jul 2006 20:57:18 -0700 From: "Douglas W. Goodall" <douglas_goodall@mac.com> To: <freebsd-mobile@freebsd.org> Subject: Regarding spurious IR7 Interrupts Message-ID: <002601c6b067$9d7ddf70$6dce46c0@dougwide>
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Intel 386 EX Embedded Microprocessor User's Manual Order Number 272485-002 Says: 9.4.3 Spurious Interrupts For both edge and level-triggered interrupts, a high level must be maintained on the IR line until after the falling edge of the first INTA# pulse (see Figure 9-18). A spurious interrupt request is generated if this stipulation is not met. A spurious interrupt on any IR line generates the same vector number as an IR7 request. The spurious interrupt, however, does not set the in-service bit for IR7. Therefore, an IR7 interrupt service routine must check the in-service register to determine whether the interrupt source was a valid IR7 (the in-service bit is set) or a spurious interrupt (the in-service bit is cleared). Respectfully, Douglas W. Goodall
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