Re: [linux-fbdev] Retrace

On Mon, Feb 7, 2000, Geert Uytterhoeven [off-list ref] wrote:

And now the bad news: the address you have to mmap() depends on the machine
type :-(

We need to find a solution for that one day or another. The iobase is not
only arch-dependant (PReP, PowerMac, CHRP...) but also machine dependant,
since it depends on the host bridge type.

Unfortunately, with weird host bridges like Apple Uni-N (that has 3
busses with 3 different io bases but the same bus number), it's almost
impossible to get it correct, or eventually by parsing /proc/device-tree.

That means that getting code that need to do io's from userland is a real
challenge. Even X is not completely correct in this regard. Ryuichi tried
to fix it at least for PowerMacs, but gave up for Uni-N based machines.


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