Date: Fri, 13 Jul 2001 12:32:36 -0500 From: Alfred Perlstein <bright@sneakerz.org> To: "Eugene L. Vorokov" <vel@bugz.infotecs.ru> Cc: freebsd-hackers@freebsd.org Subject: Re: Some questions about kernel programming Message-ID: <20010713123236.T6664@sneakerz.org> In-Reply-To: <200107131538.f6DFctQ00744@bugz.infotecs.ru>; from vel@bugz.infotecs.ru on Fri, Jul 13, 2001 at 07:38:55PM %2B0400 References: <20010712212809.F6664@sneakerz.org> <200107131538.f6DFctQ00744@bugz.infotecs.ru>
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* Eugene L. Vorokov <vel@bugz.infotecs.ru> [010713 10:24] wrote: > > ch = fubyte(uaddr); > > And one more question, does this mean that I can't use things x = *uaddr > and *uaddr = x for userspace, but always have to use fubyte() and subyte () ? > If so, what is the reason it was done like that ? Intel has an extention for i386 (FreeBSD doesn't currently use it), but it allows for something like 36bits of address space, the only problem is that you're limited to a 32bit window into the 36 bit address space. So basically, your kernel and your userland application are probably going to have different memory location, in fact the userland addresses may not even be available to the kernel without using special address registers. This is why you need these function, to do data transfer to/from alternate address spaces. -- -Alfred Perlstein [alfred@freebsd.org] Ok, who wrote this damn function called '??'? And why do my programs keep crashing in it? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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