Messages in this thread | | | From | (John Alvord) | Subject | Re: Question: Using floating point in the kernel | Date | Thu, 21 Sep 2000 11:36:17 GMT |
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On Wed, 20 Sep 2000 22:37:29 -0700, "Lyle Coder" <x_coder@hotmail.com> wrote:
>Hi >The real issue is that if you use MMX or FP state, the kernel _must_ save >and restore the original state other wise user programs will see corruption. >We all know this too well since redhat's 6.1 (I think) kernel had this >optimized MMX functions that _screwed_ up user programs. The fact is... it >is tricky to save and restore state (device not available and all). >The basic kernel itself does not provide support for kernel code to use >these registers. If some device drivers or some modifications to the kernel >are using it.. then I hope they have the save/restore path right
A 2.5-time problem is that portions of the kernel are planned to become interruptible... so saving and restoring around a certain usage would be insufficient.
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