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Message-ID: <520012D4.7020701@zytor.com>
Date: Mon, 05 Aug 2013 14:02:12 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Ondrej Zajicek <santiago@...reenet.org>
CC: David Miller <davem@...emloft.net>, dh.herrmann@...il.com,
linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
plagnioj@...osoft.com, tomi.valkeinen@...com,
Ondrej Zary <linux@...nbow-software.org>
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
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