Date: Mon, 15 Jan 2001 13:34:34 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: "Justin T. Gibbs" <gibbs@scsiguy.com> Cc: Bruce Evans <bde@zeta.org.au>, cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org, Wilko Bulte <wkb@freebie.demon.nl>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Peter Wemm <peter@netplex.com.au> Subject: Re: cvs commit: src/sys/i386/conf GENERIC Message-ID: <XFMail.010115133434.jhb@FreeBSD.org> In-Reply-To: <200101152125.f0FLPis60113@aslan.scsiguy.com>
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On 15-Jan-01 Justin T. Gibbs wrote: >>See those 'cli' and 'popfl' instrucitons? Those are _privileged_. Userland >>can't disable/enable interrupts, so we have to trap into the kernel to do >>this >>no matter what. > > All that is required in the userland implementation is the setting of a > flag so the userland thread scheduler does not perform a thread switch. > Having an interrupt fire does not have the same consequences on a userland > program as it does for the kernel. Actually, the process needs to not be switched. This is part of KSE, so you would have to set a kernel flag in the kse for this, but yes, that would work. Granted, it pessimizes the non-i386 case, but not that badly. The kernel trap to emulate only pessimizes the i386 case (though the 386 could do without extra pessimizations, and it is a bigger pessimization.) -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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