Re: m68k: trying accessing fb memory

Hi Angelo,

On Thu, Dec 13, 2012 at 7:30 PM, angelo <[email protected]> wrote:
>> You can have BDI_CAP_MAP_DIRECT for this architecture.
>> You just need to define HAVE_ARCH_FB_UNMAPPED_AREA and implement
>> get_fb_unmapped_area. Take a look at the Blackfin implementation
>> of this function. It might work without modification on m68k-nommu.
>
> yes, should be quite easy to do as you mentioned, but requires minimal
> changes in the kernel, and i must keep the unofficial changes stored
> here locally with the current tree.
>
> Of course, i can send a patch to the list, but i am using kernel 2.6.x.
> and also not sure it can be useful to anyone except me, so easy to be
> unaccepted.
>
> For this reasons, my idea is to setup 2 or 3 ioctl's at driver level:
>
> - one to get memory address (direct memory map)

That's a bit silly. If your fb_fix_screeninfo.smem_start is correctly filled in,
an application can already mmap /dev/mem using the smem_start offset.
That works even on real Linux with MMU.

On uClinux, the application can just write to the smem_start address,
without involving mmap(), right?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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