Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP)

[Peter Zijlstra <peterz@infradead.org>]

On Sat, 2010-01-16 at 18:48 -0500, Jim Keniston wrote:

> As you may have noted before, I think FP would be a special problem  
> for your approach.  I'm not sure how folks would react to the idea of  
> executing FP instructions in kernel space.  But emulating them is also  
> tough.  There's an IEEE FP emulation package somewhere in one of the  
> Linux arch directories, but I'm not sure how precise it is, and  
> dropping even 1 bit of precision is unacceptable for many  
> applications, since such errors tend to grow in complex computations  
> employing many FP instructions.

Well, we have kernel space using FP/MMX/SSE like things, its not hard if
you really need it, but in this case I think its easier than normal,
because we'll just allow it to change the userspace state because that
is exactly what we want it to do.