Messages in this thread | | | Date | Mon, 05 Aug 2013 14:02:12 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] fbdev: suppress warning when assigning vga-save/restore base |
| |
On 08/05/2013 01:29 PM, Ondrej Zajicek wrote: > > How this could even work? AFAIK these cards have to be explicitly programmed > to enable MMIO (which was not done in the patches). These patches claim that > it is for multi-domain PCI. I would guess that vgabase is NULL in common > configurations but if it is non-NULL, it probably wouldn't work, unless > there is some hardware magic that transparently converts MMIO (from CPU PoV) > to port IO (from card/PCI PoV). >
They presumably use iowrite/ioread, which use either I/O instructions or memory instructions depending on the address.
-hpa
| |