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.
next prev 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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