Re: why Does Kernel Module should not do Floating Point operation?

["Fernando Apesteguía" <fernando.apesteguia@xxxxxxxxx>]

Because the status of the FPU is not saved. You can't use MMX for the same reason.

Best regards

On 6/27/06, Manjunath_Naik < Manjunath_Naik@xxxxxxxxxx> wrote:

Hi all,

 

Why Does Kernel Module should not do Floating Point operation? If it does what is the problem?

 

Please provide more links or articles towards the reason?

 

I got the following answer from http://kerneltrap.org/node/6405 which I am not able to understand.

 

   saving and restoring the FPU state on every syscall and interrupt is just slow, so it was a design decision not to do that. architectures with more registers than i386 even decided to only use some of them in kernel code to avoid saving and restoring the whole set, or they have a second set of registers just for supervisor code. as with the FPU, code that needs the by default unsaved registers can always save them itself.

 

Please any explanation

 

 

Thanks

Manjunath Naik

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