On Tue, 14 Mar 2000, Sven LUTHER wrote:
> On Mon, Mar 13, 2000 at 10:27:14AM -0500, jsimmons@ugradlib.acsu.buffalo.edu wrote:
> >
> > > There is O_NDELAY for audio devices, is not it?
> >
> > Try opening /dev/dsp. I don't think it will work. It shouldn't. I can see
> > lots of problems here.
> >
> > > BTW, it is really surprising
> > > that I cannot run 'fbset' from XF86_FBDev anymore :-(
> >
> > Doesn't X server have keys to changes modes. I know the regular XFree86
> > servers do. I have used keys for this. If X server fb doesn't do this then
> > its broken and it should function just like other X servers.
>
> changing mode is not the only reason why one wants to run fbset, ...
Here is the main reasons why I have it so only one app can open /dev/fb at
a time. Its called SMP. Consider two apps running at the same time both
with /dev/fb opened. Problem:
1)
Both apps mmap the MMIO region. Both program the accel engine at the
same. Hey the card locks up.
2)
DRI and fbdev MMIO region. DRI is using accel engine. Some app running
from a xterm mmaps MMIO region then uses accel engine. The card locks up.
3)
Someone runs fbset while the X server is using accel engine via /dev/fb
or DRI. Card locks up. You should only change the mode when the accel
engine is idle.
Now do people agree with me that /dev/fb should only be opened once.
"Look its a text editor, no its a OS, no its Emacs"
James Simmons (o_
fbdev/gfx developer (o_ (o_ //\
http://www.linux-fbdev.org (/)_ (/)_ V_/_
http://linuxgfx.sourceforge.net
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This archive was generated by hypermail 2b29 : Wed Mar 15 2000 - 21:00:28 EST