[Pkg-oss4-maintainers] Bug#694631: FPU in OSS4

[Ben Hutchings]

On Sun, Dec 02, 2012 at 11:32:08AM -0800, NSRT Mail account. wrote:
> Ben:
> 
> The topic of FPU usage in OSS is discussed at length throughout the
> comments here:
> http://insanecoding.blogspot.com/2009/06/state-of-sound-in-linux-not-so-sorry.html
> 
> Based on what Hannu the main developer of OSS says, what OSS is
> doing currently is safe, despite how it may look otherwise. OSS is
> designed to internally save the current state of the FPU and restore
> it itself within a single use, and works properly with current
> versions of Linux.

Saving the registers (whether in a standard place or a private buffer)
is not sufficient.  See:

commit 5b1cbac37798805c1fee18c8cebe5c0a13975b17
Author: Linus Torvalds <torvalds at linux-foundation.org>
Date:   Mon Feb 13 13:56:14 2012 -0800

    i387: make irq_fpu_usable() tests more robust

and the many following changes that went into Linux 3.3.

Ben.

-- 
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
                                                              - Albert Camus