Re: [PATCH 2.4.29-pre1] radeonfb: don't try to ioreamp the entire VRAM [was: Re: why does radeonfb work fine in 2.6, but not in 2.4.29-pre1?]

["Antonino A. Daplas" <adaplas@hotpop.com>]

On Thursday 02 December 2004 04:37, Kronos wrote:
> Il Wed, Dec 01, 2004 at 05:25:52PM +0100, Geert Uytterhoeven ha scritto:
> > > Make fb layer aware of the difference between the ioremap()'ed VRAM and
> > > total available VRAM.
> > > smem_len in struct fb_fix_screeninfo still contains the amount of
> > > physical VRAM (reported to userspace via FBIOGET_FSCREENINFO ioctl) and
> > > the new field mapped_vram contains the amount of VRAM actually
> > > ioremap()'ed by drivers (used in read/write/mmap operations).
> > > Since there was unused padding at the end of struct fb_fix_screeninfo
> > > binary compatibility with userspace utilities is retained.
> > > If mapped_vram is not set it's assumed that the entire framebuffer is
> > > mapped, thus other drivers are unaffected by this patch.
> > >
> > > The patch has been tested by Jurriaan <thunder7@xs4all.nl>.
> > >
> > > Signed-off-by: Luca Tettamanti <kronos@people.it>
> > >
> > > --- a/include/linux/fb.h	2004-11-30 18:30:08.000000000 +0100
> > > +++ b/include/linux/fb.h	2004-11-30 18:33:00.000000000 +0100
> > > @@ -126,7 +126,8 @@
> > >  					/* (physical address) */
> > >  	__u32 mmio_len;			/* Length of Memory Mapped I/O  */
> > >  	__u32 accel;			/* Type of acceleration available */
> > > -	__u16 reserved[3];		/* Reserved for future compatibility */
> > > +	__u32 mapped_vram;		/* Amount of ioremap()'ed VRAM */
> > > +	__u16 reserved[1];		/* Reserved for future compatibility */
> > >  };
> >
> > I don't really like this patch. mapped_vram doesn't matter for user space
> > at all, so it does not belong to fb_fix_screeninfo.
>
> Hmm, it looked sensible to me since it's the max amount of data that
> userspace can read (or write) from /dev/fb%d.

Userspace already use fix.line_length * var.yres_virtual to compute the
amount it can access, which is not necessarily equal to the mapped vram.

> Putting mapped_vram in fb_info would be acceptable?

Yes, that is a more sensible solution.

Tony




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