Subject: Re: framebuffer mmap access
To: Scott Reynolds <>
From: Brett D. Slager <>
List: tech-kern
Date: 03/21/1999 23:26:46
In message <>, you wrote:
> This will put the display, whether console or not, into mapped mode, and
> mmap() will work fine.  (To revert back to the emulation, use

I found this after I sent that message.

> >   It's perfectly reasonable to want to
> >   mmap the display on a tga regardless of any text emulations.
> For a display that operates exclusively in a bitmapped mode, I'd agree.  On
> the other hand, the interface as it stands allows the implementor to have a
> way to switch between a bitmapped display for framebuffer access and a
> hardware-based text mode, and have well-defined results in each case.
> --scott

How about a new flag that can be set by the WSDISPLAYIO_SMODE ioctl:
Mixed mmap and text access would be allowed under this mode, and a framebuffer
driver would be able to set this mode by default.
X servers that take advantage of accelerated features incompatible with
simple framebuffer access would have to use WSDISPLAYIO_MODE_MAPPED.
Also WSDISPLAYIO_MODE_SIMPLE would disable the use of features incompatible
with simple framebuffer access by the text emulation raster driver.

Would that take care of your compatibility problem?