Re: [PATCH] fbdev: suppress warning when assigning vga-save/restorebase

From: H. Peter Anvin
Date: Mon Aug 05 2013 - 17:02:58 EST

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.


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