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Re: [Qemu-devel] [PATCH 12/16] vga: Convert to isa_register_portio_list.

From: Richard Henderson
Subject: Re: [Qemu-devel] [PATCH 12/16] vga: Convert to isa_register_portio_list.
Date: Sun, 18 Sep 2011 07:16:28 -0700
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20110906 Fedora/3.1.14-1.fc14 Thunderbird/3.1.14

On 09/18/2011 06:45 AM, Avi Kivity wrote:
>> +    /* The PCI-ISA bridge should have been configured properly such that
>> +       this works for PCI devices as well.  This only supports one bridge,
>> +       but "secondary" VGA cards are generally accessed by MMIO only 
>> anyway.  */
>> +    isa_register_portio_list(NULL, 0x3b0, vga_portio_list, s, "vga");
>>       memory_region_init_io(vga_mem,&vga_mem_ops, s,
> This is called even for pci machines which have no ISA bus (and even
> if they did, the code should work wit the pci bus, not ISA). The code
> should return the portio list of the caller to register, or perhaps
> accept a callback to do the registration.

You're over-thinking this.  It's all legacy ISA crap full stop.
If the machine doesn't have a PCI-ISA bridge, then the machine will
also be prepared to access the VGA registers via its BARs.

In such a case we just should skip this entire section.  Probably
isa_register_portio_list should simply notice no ISA bus has been
registered and do nothing.


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