Date: Thu, 12 Apr 2007 13:21:31 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Jung-uk Kim <jkim@FreeBSD.org> Cc: freebsd-emulation@FreeBSD.org, Juergen Lock <nox@jelal.kn-bremen.de>, freebsd-ports@FreeBSD.org Subject: Re: kqemu+amd64: fpudna in kernel mode Message-ID: <461E082B.8040401@icyb.net.ua> In-Reply-To: <200704111307.17455.jkim@FreeBSD.org> References: <461CFD4B.4020801@icyb.net.ua> <200704111307.17455.jkim@FreeBSD.org>
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on 11/04/2007 20:07 Jung-uk Kim said the following: > On Wednesday 11 April 2007 11:22 am, Andriy Gapon wrote: >> I get swarms of messages "fpudna in kernel mode" in system log when >> I run qemu with kqemu on FreeBSD 6.2 amd64 host with Windows XP >> 32-bit guest. I noticed that someone reported this problem a while >> ago: >> http://lists.freebsd.org/pipermail/freebsd-emulation/2006-February/ >> 001800.html > > This happens because we do not allow FP instructions in kernel mode as > the error message suggested. Executing FP instructions in kernel > mode requires expensive save/restore cycles for FP states. > Jung-uk, thank you for the reply but there is still something not clear to me. I've read Bruce's response also, but I must admit I couldn't understand much. So, if floating point instructions cause trap then they apparently fail (or no ?), then why does (k)qemu executes them anyway ? And how (k)qemu is able to proceed normally after such failure ? -- Andriy Gapon
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