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From: "Richard B. Johnson" <root@chaos.analogic.com>
To: ndiamond@despammed.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: How to use floating point in a module?
Date: Mon, 31 May 2004 22:11:20 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.53.0405312201450.7675@chaos> (raw)
In-Reply-To: <200405310152.i4V1qNk03732@mailout.despammed.com>

On Sun, 30 May 2004 ndiamond@despammed.com wrote:

> A driver, implemented as a module, must do some floating-point
> computations including trig functions.  Fortunately the architecture
> is x86.  A few hundred kilograms of searching (almost a ton of searching :-) seems to reveal the following possibilities.
>

Since you are using one of those Windows mailers and didn't enter a
single end-of-line character, I detect that this is probably one
of those trolls. Nevertheless, the use of floating-point is forbidden
within the kernel. Period. Because anybody who thinks they need
floating-point mathematics within the kernel is completely without
a clue, the floating-point context is not saved/restored during system
calls.

You must pair a user-mode program (usually called a daemon) with
the kernel-mode interface to your hardware (your module). This
combination will provide whatever functionality you require. The
user-mode daemon does the math and probably a lot of other things
as well.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.26 on an i686 machine (5583.66 BogoMips).
            Note 96.31% of all statistics are fiction.



  parent reply	other threads:[~2004-06-01  2:11 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-05-31  1:52 ndiamond
2004-05-31  2:18 ` Måns Rullgård
2004-05-30 22:39   ` Calvin Spealman
2004-05-31  4:28   ` Linus Torvalds
2004-05-31  3:57     ` Calvin Spealman
2004-05-31  3:59 ` Matt Mackall
2004-05-31  4:11 ` Stephen Smoogen
2004-05-31 14:55 ` Scott Robert Ladd
2004-06-01  2:11 ` Richard B. Johnson [this message]
2004-05-31  2:50 ndiamond
2004-05-31  4:02 ` Chris Friesen
2004-05-31  5:44 ` Ian Kent
2004-05-31  6:13   ` Peter Williams
2004-05-31 13:39   ` Horst von Brand
2004-05-31 20:12   ` Michal Jaegermann
2004-05-31 20:23     ` Hugo Mills
2004-05-31 22:43     ` Peter Williams
2004-05-31 20:38 Manfred Spraul
2004-05-31 21:11 ` Horst von Brand
2004-06-01  0:38 ndiamond
2004-06-01 20:52 ` H. Peter Anvin
2004-06-01  2:27 ndiamond
2004-06-02  5:52 ndiamond
2004-06-02 19:31 ` Valdis.Kletnieks

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