Newsgroups: comp.arch Path: utzoo!henry From: henry@utzoo.uucp (Henry Spencer) Subject: Re: Is the Intel memory model safe from NO-ONE ?!? Message-ID: <1988May12.162207.16764@utzoo.uucp> Organization: U of Toronto Zoology References: <353@cf-cm.UUCP> <3095@edm.UUCP>, <20618@think.UUCP> Date: Thu, 12 May 88 16:22:07 GMT > ... it traps into SUPERVISOR mode, even though the program > that executed the divide instruction was running in USER mode. Why > should a zero-divide need to be handled by the protected kernel, > rather than simply trapping to a user handler? Probably because practically every machine in existence routes *all* traps and interrupts to the kernel, which can pass them on to the user if it pleases. I know of no machine, offhand, whose hardware has any notion of a "user handler". -- NASA is to spaceflight as | Henry Spencer @ U of Toronto Zoology the Post Office is to mail. | {ihnp4,decvax,uunet!mnetor}!utzoo!henry