Re: [Linux-fbdev-devel] mmap method usage

[Emmanuel M. <emm...@re...>]

Geert Uytterhoeven <ge...@li...> writes:

> On 29 Jan 2002, Emmanuel Michon wrote:
> > I derived a fb implementation from vfb and I noticed
> > the latter does not implement the mmap() function.
> > So I guess X with fbdev does not run on top of vfb...

When I say it does not run I don't know where the pixel go if mmap()
fails but it seems it's up ;-) It just does not really draw anything
even in the vmalloc'd area

> Indeed not. Until someone ports the mmap() trick from vga256fb
> (http://www.kyuzz.org/antirez/vga256fb.html) to vfb.

I think this trick won't work with normal vmalloc'd RAM: somebody has
to render the virtual-physical mapping permanent walking the pages
to set them reserved (something like rvmalloc found in bttv).

Then mmap() implementation requires a call to remap_page_range for
each physically contiguous region (one per 4K I'm afraid)

Sincerely yours,

-- 
Emmanuel Michon
Chef de projet
REALmagic France SAS
Mobile: 0685316107 GPGkeyID: D2997E42