# Re: \[PATCH\] framebuffer: fix screen corruption when copying

- From: Mikulas Patocka \<mpatocka@redhat.com\>
- Date: 2014-09-17 11:44:29 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2014/09/4335670
- Thread: https://ratatoskr.run/linux-fbdev/2014/09/4335068/t.md

```text


On Wed, 17 Sep 2014, Geert Uytterhoeven wrote:

> Hi Mikulas,
> 
> On Tue, Sep 16, 2014 at 6:38 PM, Mikulas Patocka [ref] wrote:
> > The patch also removes the references to fb_memmove in the code that is
> > commented out because fb_memmove was removed from framebuffer subsystem.
> 
> I'd leave it as-is. Using plain memmove() is not correct, as it should operate
> on MMIO space, not RAM. On x86 it works with memmove(), though, but
> not on all architectures.
> 
> Gr{oetje,eeting}s,
> 
>                         Geert

That code is disabled with #if 0. So it doesn't matter if it's incorrect 
in some specific situation.

The purpose of that disabled code is to be able to verify that the bug is 
in bitcpy_rev. I get screen corruption - so I enable that "memmove" 
statement - the screen corruption goes away - so I know that the bug is in 
bitcpy_rev.

Mikulas
```