Re: Intel floating-point initialization

H. Peter Anvin (hpa@transmeta.com)
19 May 1998 10:36:11 GMT

Followup to: <19980519101452.11458@pauillac.inria.fr>
By author: Xavier Leroy <Xavier.Leroy@inria.fr>
In newsgroup: linux.dev.kernel
>
> I beg to disagree with Linus. The parent process/thread may have set
> the FPU control word to a non-default value (i.e. change rounding
> modes, etc). The programmer legitimely expects the child process to
> inherit those settings (just like it inherits pretty much everything
> else from its parent).
>

If the FPU registers are otherwise preserved across a system call,
they should be copied by fork(). Otherwise it will not work properly
if you use floating point in the same routine that does a fork()
(remember, to the C compiler, fork() is just another function.)

-hpa

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