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Re: [PATCH] Import updates from i386's i8259.c

To: "Maciej W. Rozycki" <>
Subject: Re: [PATCH] Import updates from i386's i8259.c
From: Sergei Shtylyov <>
Date: Wed, 06 Dec 2006 16:53:40 +0300
Cc: Ingo Molnar <>,, Ralf Baechle <>,
In-reply-to: <>
Organization: MontaVista Software Inc.
Original-recipient: rfc822;
References: <> <> <> <> <> <>
User-agent: Mozilla/5.0 (X11; U; Linux i686; rv:1.7.2) Gecko/20040803

Maciej W. Rozycki wrote:

+static struct irq_chip i8259A_chip = {
+       .name           = "XT-PIC",
+       .mask           = disable_8259A_irq,
+       .unmask         = enable_8259A_irq,
+       .mask_ack       = mask_and_ack_8259A,

  I wonder whose idea was to call this device XT-PIC. XT never had dual 8259A
PICs and so was capable of handling only 8 IRQs. Dual 8259A was first used in
the AT class machines...

 Ask Ingo, perhaps... ;-)

   Ask and be ignored. :-)

I think he was perfectly right, though -- this is a pair of PC/XT-class PICs.

Coupled as only in PC/AT-class machines. So, this XT qualification is actually meaningless. It's 8259A, that's all.

And with the "IO-APIC-edge" and "IO-APIC-level" alternatives back when the concept of IRQ controllers was introduced, "XT-PIC" rather than "8259A" sounded quite right.

   I don't follow you here.


WBR, Sergei

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