I'm not suggesting that XFree86 take on the responsibility for these drivers! What I'm saying is it doesn't seem like such a big deal to simply have *support* for a vblank mechanism. Leave the details of how it occurs up to a particular set of drivers. If people need vblank badly enough, the driver support will get written. You're right that other platforms might not support this so easily -- but so what? If people really need it, they'll write it.
I guess I'm proposing some sort of X extension that allows a particular X request to be tagged as "synced to vblank." For example a XCopyArea request could be preceded by another request (call it XRequestVerticalSync) that indicates to the server that the operation shouldn't be performed until a vblank period.
This is a very simple change. If no driver support exists for vertical sync, the server can just politely ignore the request, and do the operation whenever it feels like it. This would at the very least provide a framework for individual driver writers to start working on a kernel interface.
Scott Long
On Fri, 1 Nov 2002 09:48:54 -0800
Ian Romanick <[EMAIL PROTECTED]> wrote:
It's not impossible, but it does require a kernel driver. That makes it
more than just "a hairy problem" for XFree86. Think about it. You'd likely
need a *different* kernel module for every combination of hardware,
operating system (aren't there some XFree86 supported systems that don't use
loadable kernel modules?), and platform (i.e., X86 vs. Alpha vs. PowerPC,
etc.).
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