Date: Fri, 30 Aug 2002 13:30:32 -0700 From: "Balaji, Pavan" <pavan.balaji@intel.com> To: "'Julian Elischer'" <julian@elischer.org>, "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: <3D386AED1B47D411A94300508B11F18704AD69D3@fmsmsx116.fm.intel.com>
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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..
Also, if this is right, how do I get the kernel virtual address it's
associated to? The function returns a void.
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..
>
>
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