On Mon, 2007-08-20 at 17:27 +0200, Matthias Hopf wrote: > Because we won't get an ix86 emulator in kernel space, Linus and others > have been pretty clear about that. Graphics hardware sometimes needs > BIOS calls, on non-i386 hardware that has to be done by an emulator.
Post-boot, for the primary card, I don't know what hardware requires BIOS calls at ths point. We certainly shouldn't encourage people to build drivers that do. > This is just one reason. One other is that you want to address graphics > in user space anyways for performance reason. Of course, mode setting > isn't exactly performance critical. Without mode setting capabilities in the kernel, we cannot get S3 support working reliably. What we've done, however, is split the mechanism from the policy so that the kernel piece does no more than actually drive the hardware; configuration and the rest remain in user space where they belong. > You just cannot compare graphics hardware with any other hardware at > all. Graphics chips are more complicated than any CPU on the market, > which other hardware type is similar? Even high-speed interconnects like > infiniband are trivial compared to that. The kernel driver manages video mode selection, memory, interrupts, DMA and the basic ring. The rest of the driver is in user space, including all of the complicated language compilation bits. > That said, I'm not 100% confident that the currently discussed way is > the right solution. OTOH I don't know the "right" solution myself > either... The correct solution is a kernel driver that manages the card configuration and resources. Anything else eliminates many of the desirable benefits of providing a kernel driver in the first place. -- [EMAIL PROTECTED]
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