Re: x86 IO-APIC and IRQ questions

From: Chuck Ebbert (76306.1226@compuserve.com)
Date: Thu Apr 17 2003 - 22:03:26 EST

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Maybe in reply to: Chuck Ebbert: "x86 IO-APIC and IRQ questions"
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Chuck Ebbert wrote:

> And why are the IRQ entry points (in 2.4.20) not 16-byte aligned?
> Up until IRQ0x0b everything is OK because the actual stubs are only
> 7+1 bytes long, but after that the jmp instruction needs a 32-bit
> offset and they are 10+2 bytes. This puts IRQ #15 and #19 four
> bytes from the end of a 16-byte cache line, and their first
> instructions are 5 bytes long.

This should help:

--- linux-2.4.20aa1/arch/i386/kernel/i8259.c Tue Sep 18 02:03:09 2001
+++ linux-2.4.20irq/arch/i386/kernel/i8259.c Thu Apr 17 22:22:12 2003
@ -35,8 +35,6 @
  * interrupt-controller happy.
  */

-BUILD_COMMON_IRQ()
-
#define BI(x,y) \
         BUILD_IRQ(x##y)

@ -52,6 +50,8 @
  */
BUILD_16_IRQS(0x0)

+BUILD_COMMON_IRQ()
+
#ifdef CONFIG_X86_IO_APIC
/*
  * The IO-APIC gives us many more interrupt sources. Most of these

--
 Chuck
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Next message: Jason Giglio: "Sockets hanging in CLOSING state for hours"
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Maybe in reply to: Chuck Ebbert: "x86 IO-APIC and IRQ questions"
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