Re: Saving the Floating Point State
Re: Saving the Floating Point State
- Subject: Re: Saving the Floating Point State
- From: Michael Smith <email@hidden>
- Date: Mon, 26 Apr 2010 08:35:08 -0700
On Apr 25, 2010, at 7:02 PM, Quinn wrote: At 13:40 -0700 23/4/10, Duane Murphy wrote: Does OS X/Darwin have a function for saving and restoring the state of the floating pointer registers?
No. The Darwin model is that you should use the floating point unit at will; the kernel will notice, trap, save the user's FP state, clear the FP state, and continue running your code. At that point the kernel knows that the FP unit contains kernel stuff, and preserve it across kernel preemptions, and restores the user FP state when the thread returns to user space.
Note that this only applies to the use of FP resources in a user context, whereas I believe the OP was asking about the use of same in the kernel.
Kernel code must not use FP resources.
= Mike
-- True terror is to wake up one morning and discover that your high school class is running the country. -- Kurt Vonnegut
|
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Darwin-kernel mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden