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Re: [PATCH 2/2] via-ide: Also emulate non 100% native mode

From: Mark Cave-Ayland
Subject: Re: [PATCH 2/2] via-ide: Also emulate non 100% native mode
Date: Sun, 1 Mar 2020 19:40:02 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0

On 01/03/2020 18:53, BALATON Zoltan wrote:

> On Sun, 1 Mar 2020, BALATON Zoltan wrote:
>> is not legacy mode but "not 100% native mode". The prog-if is set to 0x8a 
>> which
>> corresponds to native mode but this is what the Linux fixup function does, 
>> firmware
>> sets it to 0x8f which means native mode.
> I mean, 0x8a legacy mode and 0x8f native mode, I see firmware poking 0x8f and 
> Amiga
> like OSes reading that yet expecting legacy interrupts. Linux fixes up 
> prog-if so its
> driver detects legacy interrupts but still uses ioports from PCI BARs.

I see. Note that it is also possible to have a prog-if value of 0x80 which is 
the hardware is locked into legacy mode via a pull-down resistor. Perhaps this 
is the
case for Pegasos, since it would explain why attempts to switch the mode via 
are ignored?

I don't see the PCI BARs being a problem since native drivers wouldn't touch the
memory/IO space enable bits, and the BARs are disabled by default. It could 
just be
that the VIA chipset simply doesn't lock the PCI memory/IO space bits in
compatibility mode if an OS does decide to use them and program the BARs as it 
in native mode.



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