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:
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.
This is correct. We want to add a process that uses FP resources in the kernel.
Kernel code must not use FP resources.
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? ...Duane -----BEGIN PGP SIGNATURE----- Version: PGP Desktop 9.10.0 (Build 500) Charset: US-ASCII wsBVAwUBS9W2AErg9acQ4r2CAQiyfwf/Tt020uXHYNw0VA27ftKJOyOlJSFFSCjr FY789YoIMuiP4kb6cETo7fM+iOWkCNAoQaIioC9WYCs5OYo/NIMalCNp4vV149XB Z4W8rFA6KH0czKXAjC3x1iuR+T8HpeNXG22dQLN8E+OClX9UxXPg9G7AX4VSRd7D scypb7REUCglLbrsbq0vM8ghrLfo+0IU8nugJNZqbnXzZ32f/c4nnxGOPiObeFIF GM1W4BQhsWz4J9Sdg0DF4xomKAZYA7d/LmzQCuvXBonqMhBGBaxGxBNzefRy+1jN 0BAs7En6OisMG4SUjPQSTwrReKxqOuMoHjvBHKtXvaA8pLdYA+QI0g== =blSK -----END PGP SIGNATURE----- _______________________________________________ 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... This email sent to site_archiver@lists.apple.com