Date: Fri, 30 Aug 2002 13:52:35 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: "Balaji, Pavan" <pavan.balaji@intel.com> Cc: "'freebsd-hackers@freebsd.org'" <freebsd-hackers@freebsd.org> Subject: RE: Copying from Virtual Address Space to Physical Address Message-ID: <Pine.BSF.4.21.0208301349330.4649-100000@InterJet.elischer.org> In-Reply-To: <3D386AED1B47D411A94300508B11F18704AD69D3@fmsmsx116.fm.intel.com>
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On Fri, 30 Aug 2002, Balaji, Pavan wrote: > > I'm a little bit confused about this vmapbuf() thing. This is what I think, > correct me if I'm wrong. > > I have this User Virtual address, userbuf --> associated to physadd > > Now, I do vmapbuf(physadd), and I get a Kernel Virtual Address associated to > this "physadd". Now, I write to this Kernel Virtual Address and it reflects > in userbuf? OhmyGod!!! Is that what it's supposed to do? Hope it doesn't > oops my machine.. no that is correct. this function is for making user space buffers map into kernel space.. you just want the second half of this.. Now I have a question for you.... how do you know what pages you want to map into kernel virtual space? > > Also, if this is right, how do I get the kernel virtual address it's > associated to? The function returns a void. The buf steucture is updated to hold KV addresses for the region. 'bp' is a pointer to a complicated struct that defines the buffer, not to the address of the buffer itself. > > Thanx. > > Pavan Balaji, > Intel Corporation > Email: pavan.balaji@intel.com > > "Only the Paranoid Survive" -- Andy Grove > > > > -----Original Message----- > > From: Julian Elischer [mailto:julian@elischer.org] > > Sent: Friday, August 30, 2002 3:20 PM > > To: Balaji, Pavan > > Cc: 'freebsd-hackers@freebsd.org' > > Subject: Re: Copying from Virtual Address Space to Physical Address > > > > > > > > > > On Fri, 30 Aug 2002, Julian Elischer wrote: > > > > > Physio() does this.. first it finds the physical addresses > > of the user > > > pages targetted, then it maps those pages into kernel > > space, and then it > > > initiates IO to them. (this actually needs to change but > > for now it's > > > true. > > > > > > to correct myself.. > > physio() calls vmapbuf(bp) in order to do it.. > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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