From owner-freebsd-hackers  Sun Nov 30 21:23:38 1997
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Date: Sun, 30 Nov 1997 21:17:38 -0800 (PST)
From: Julian Elischer <julian@whistle.com>
To: John-Mark Gurney <gurney_j@resnet.uoregon.edu>
cc: "John S. Dyson" <toor@dyson.iquest.net>, j_mini@efn.org,
        hackers@freebsd.org
Subject: Re: dirty bit in page allocations.
In-Reply-To: <19971130125201.44588@hydrogen.nike.efn.org>
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I'm pretty willing to bet that the frame-buffer, while linear, will
probably be broken on page boundaries,
in which case the page handling VM code can do it for you.
that's what mmap() on device drivers was invented for..
no?


On Sun, 30 Nov 1997, John-Mark Gurney wrote:

> John S. Dyson scribbled this message on Nov 30:
> > Jonathan Mini said:
> > >   I need to read and set the dirty bit on pages of allocated kernel memory. I
> > > allocate the memory via malloc, and then export it to the userland via mmap.
> > > What I need to do is clear and test the dirty bit on those pages. This way, I
> > > can dump only those pages which have been modified instead of the entire set
> > > of pages.
> > >   What are the functions/macros/etc which will allow me to do this?
> > > 
> > What, exactly, are you trying to do?  (I am not trying to be snotty or anything,
> > but there are easy ways to do certain things, and more difficult ways :-)).  I
> > might be able to help you put something together that is easy.
> 
> well... since Mini is still a sleep...  basicly he is writing code that
> will use the VBE spec to interface with the video card and display
> graphics...  as the spec doesn't force the card to have a linear frame
> buffer he is writing code that will "simulate" a linear frame buffer
> for the application..
> 
> he then needs to find out what pages in the simulated linear frame
> buffer has been modified and only write those pages out to the video
> card...
> 
> -- 
>   John-Mark Gurney                          Modem/FAX: +1 541 683 6954
>   Cu Networking
> 
>   Live in Peace, destroy Micro$oft, support free software, run FreeBSD
>