Re: Float numbers in module programming

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Wed, 29 Mar 2006, beware wrote:

> Hi
>
> i wonder if it is available to use float numbers in a module programming.
> Because, when I'm look for the param_get functions, i find them only
> for integers (long, short, and others) but none for the float numbers.
>
> Thanks for yours answer.
>
> bye
> -

This used to be a FAQ. The floating-point coprocessor in ix86
machines is a shared resource. There is only one. Therefore,
the state of the floating-point unit needs to be saved and
restored across all context switches. Because this is expensive
in terms of CPU time used, it is not saved and restored during
system calls. This means that if you use the coprocessor in
the kernel, you may screw up somebody's mathematics, causing
the airplane to go off course and crash into the Getchey-
Goomy swamp. If this is okay, then fine. Otherwise, don't
use the coprocessor inside kernel code.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.15.4 on an i686 machine (5589.42 BogoMips).
Warning : 98.36% of all statistics are fiction, book release in April.
_


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