Ch 5: Why both kernel headers?

Ian Molton spyro at
Wed Sep 15 14:08:22 PDT 2004

On Wed, 15 Sep 2004 19:56:08 +0200
Laurens Blankers <laurens.blankers at> wrote:

> I thought programs communicated with the kernel through interrupts
> only. So what does the kernel have to do with ABI defs?

Thats just enough knowledge to shoot yourself in the foot with there.

userspace does NOT use interrupts to communicate with the kernel, those
are a hardware thing.

userspace uses *software* interrupts to communicate with the kernel,
which behave in a very similar manner but arent triggered by hadrware
IRQ lines.

at this point the ABI is *everything*. the kernel and userspace must
agree on how the data they shre in this event is formatted, or the shit
_will_ hit the fan.

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