Re: [PATCH 12/14] x86_64 irq: Add constants for the reserved IRQ vectors.

From: Eric W. Biederman
Date: Sun Feb 25 2007 - 06:17:42 EST


Pavel Machek <pavel@xxxxxx> writes:

> Hi!
>
>> For the ISA irqs we reserve 16 vectors. This patch adds constants for
>> those vectors and modifies the code to use them. Making the code a
>> little clearer and making it possible to move these vectors in the future.
>
>
>> /*
>> * Vectors 0x20-0x2f are used for ISA interrupts.
>> */
>> +#define IRQ0_VECTOR FIRST_EXTERNAL_VECTOR
>> +#define IRQ1_VECTOR IRQ0_VECTOR + 1
>
> Maybe IRQ_VECTOR(1) would be similary readable, and would avoid
>
>> +#define IRQ2_VECTOR IRQ0_VECTOR + 2
>> +#define IRQ3_VECTOR IRQ0_VECTOR + 3
>> +#define IRQ4_VECTOR IRQ0_VECTOR + 4
>> +#define IRQ5_VECTOR IRQ0_VECTOR + 5
>> +#define IRQ6_VECTOR IRQ0_VECTOR + 6
>> +#define IRQ7_VECTOR IRQ0_VECTOR + 7
>> +#define IRQ8_VECTOR IRQ0_VECTOR + 8
>> +#define IRQ9_VECTOR IRQ0_VECTOR + 9
>> +#define IRQ10_VECTOR IRQ0_VECTOR + 10
>> +#define IRQ11_VECTOR IRQ0_VECTOR + 11
>> +#define IRQ12_VECTOR IRQ0_VECTOR + 12
>> +#define IRQ13_VECTOR IRQ0_VECTOR + 13
>> +#define IRQ14_VECTOR IRQ0_VECTOR + 14
>> +#define IRQ15_VECTOR IRQ0_VECTOR + 15
>
> ...these defines?

It would, and mostly I like it. However, of the 1500+ possible irqs
exactly 16 have a reserved vector. IRQ_VECTOR(N) does not convey
that in fact it conveys the opposite impression.

So I think the code is more maintainable with the distinct
definitions.

Eric
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