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SubjectRe: SVGA kernel chipset drivers.


First please note I'm not relpying to anyones message in particular, I've
just got a few things that I think need to be said.


I can see several reasons for people wanting to "enhance" the
kernel/graphics card "cooperation":

1. Security, setuid is a big problem just to do graphics

2. Speed, lots calls to ioperm()/iopl() can't be good for
performance

3. Tidyness, Some might say it makes more sense for the
kernel to do for graphics what it does for sound.

4. Quicker uptime with new graphics cards in userlevel if we
can assume some basic interface. (JoeWhizo new graphics
card can run, but not at it's best X on last years kernel
even when we don't have any specs for it yet.)



My comments on these "reasons":

1. This problem is already solved -> POSIX.6, the process
(XF86_*, or SVGAlib) gets the single priv to use ioperm/iopl and can't do
anyother things a setuid0 binary can.

(For those that don't know, I'm currently working on the POSIX.6
implementation and should have something useable for a more general beta
for putting into 2.1.x)

2. I can only see a help here if the speed problem is the user<->kernel
jumpping around.

3. Sometimes a good idea - look at VFS and the Soundcard stuff nice and
tidy they could all be a terible hack and random interfaces from userlevel
libs to kernel.

4. This can be important and very helpfull, eg I've found very few
videocards that don't work in Windoze bog standard VGA mode. It would be
nice if Linux could have this sort of basic expectation as well, graphical
install programs for first time users wither they be X/SVGA or other.




Just for the record I'm writting this in a 80x50 textmode with a thin
font, but yesterday I was running X - why? variety is the spice of life!

I'm willing to try kernel level graphics stuff if it gets me better
performance/security/stability - or even just one providing it doesn't
compromise the others.


I don't think SVGAlib as it stands is cutting is, and I really don't care
how many XServers there are - I've got 3 different Xservers on my Sun at
work and only one XF86 server at home, disk space bloat isn't an issue -
you only install the one you really need and if the SVGA one is a bloat
that causes you concern then you need a better install program that
relinks with only the card you have in your machine (but as I understand
life in Linux this don't really matter much anyway because of
demandloading and friends).



Whew.. there I've said what I had to say do with it what you wish.

--
Darren J Moffat



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