From: "H. Peter Anvin" <hpa@zytor.com>
To: Ondrej Zajicek <santiago@crfreenet.org>
Cc: David Miller <davem@davemloft.net>,
dh.herrmann@gmail.com, linux-fbdev@vger.kernel.org,
linux-kernel@vger.kernel.org, plagnioj@jcrosoft.com,
tomi.valkeinen@ti.com, Ondrej Zary <linux@rainbow-software.org>
Subject: Re: [PATCH] fbdev: suppress warning when assigning vga-save/restore base
Date: Mon, 05 Aug 2013 21:14:05 +0000 [thread overview]
Message-ID: <5200159D.1010106@zytor.com> (raw)
In-Reply-To: <520012D4.7020701@zytor.com>
On 08/05/2013 02:02 PM, H. Peter Anvin wrote:
> 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.
>
So the confusion really is in the iowrite interface, which can take
either a physical port address or a virtual memory address...
-hpa
WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Ondrej Zajicek <santiago@crfreenet.org>
Cc: David Miller <davem@davemloft.net>,
dh.herrmann@gmail.com, linux-fbdev@vger.kernel.org,
linux-kernel@vger.kernel.org, plagnioj@jcrosoft.com,
tomi.valkeinen@ti.com, Ondrej Zary <linux@rainbow-software.org>
Subject: Re: [PATCH] fbdev: suppress warning when assigning vga-save/restore base
Date: Mon, 05 Aug 2013 14:14:05 -0700 [thread overview]
Message-ID: <5200159D.1010106@zytor.com> (raw)
In-Reply-To: <520012D4.7020701@zytor.com>
On 08/05/2013 02:02 PM, H. Peter Anvin wrote:
> 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.
>
So the confusion really is in the iowrite interface, which can take
either a physical port address or a virtual memory address...
-hpa
next prev parent reply other threads:[~2013-08-05 21:14 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-04 17:25 [PATCH] fbdev: suppress warning when assigning vga-save/restore base David Herrmann
2013-08-04 17:25 ` David Herrmann
2013-08-04 17:33 ` H. Peter Anvin
2013-08-04 17:33 ` H. Peter Anvin
2013-08-05 1:51 ` David Miller
2013-08-05 1:51 ` David Miller
2013-08-05 20:29 ` Ondrej Zajicek
2013-08-05 20:29 ` Ondrej Zajicek
2013-08-05 21:02 ` H. Peter Anvin
2013-08-05 21:02 ` H. Peter Anvin
2013-08-05 21:14 ` H. Peter Anvin [this message]
2013-08-05 21:14 ` H. Peter Anvin
2013-08-05 22:29 ` David Miller
2013-08-05 22:29 ` David Miller
2014-02-10 11:23 ` Tomi Valkeinen
2014-02-10 11:23 ` Tomi Valkeinen
2014-02-10 11:32 ` David Herrmann
2014-02-10 11:32 ` David Herrmann
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