Date: Sat, 10 Mar 2007 18:54:27 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: "Michael M. Press" <deathjestr@gmail.com> Cc: maslanbsd@gmail.com, freebsd-hackers@freebsd.org, cokane@cokane.org Subject: Re: Floating-point in kernel space Message-ID: <20070310185427.4fc3c033@Magellan.Leidinger.net> In-Reply-To: <44b564930703091510r35e8c56eke0c8761fa5f234e9@mail.gmail.com> References: <319cceca0703090116p7e768630qd055be57bbe4953@mail.gmail.com> <200703091021.l29ALLVw067285@lurza.secnetix.de> <346a80220703091044p5759e6do521065203299c26b@mail.gmail.com> <44b564930703091510r35e8c56eke0c8761fa5f234e9@mail.gmail.com>
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Quoting "Michael M. Press" <deathjestr@gmail.com> (Fri, 9 Mar 2007 18:10:25 -0500): > > I think i've seen somewhere but i don't remember that floating point > > arithmetic is not allowed in kernel space, if that's right, can anyone > > please tell why ??? > > and why not not emulate the floating point in kernel space ??? > > That's nonsense! Floating point arithmetic is absolutely allowed in > kernel space, it's just that user space applications don't tend to > like their data being mangled very much. > > I remember this topic coming up a short while ago on this list. > Perhaps if there is sufficient need someone could implement a pair > of floating-point save/restore functions to allow floating-point > (or MMX) calculations to be used in the kernel only when needed. > Something like the EngSaveFloatingPointState/ > EngRestoreFloatingPointState functions that Windows has. Have a look at the FPU item on the ideas page. There you find a patch for something like this. Bye, Alexander. -- If there was any justice, my face would be on a bunch of crappy merchandise! -- Homer Simpson Flaming Moe's http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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