site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On Apr 26, 2010, at 8:35 AM, Michael Smith wrote: On Apr 25, 2010, at 7:02 PM, Quinn 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. This is correct. We want to add a process that uses FP resources in the kernel. Huh? That seems like an onerous restriction. Can someone please explain this a little better? There are some useful algorithms that take use floating point registers. How might I take advantage of these algorithms? By doing them in user space? Why does your code need to run in protected mode? -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... On Apr 26, 2010, at 8:49 AM, Duane Murphy <duanemurphy@mac.com> wrote: At 13:40 -0700 23/4/10, Duane Murphy wrote: Kernel code must not use FP resources. This email sent to site_archiver@lists.apple.com