Re: [Qemu-devel] [PATCH v3 5/6] vga: Use linear mapping + dirty logging in chain 4 memory access mode

[Blue Swirl]

On Wed, Sep 14, 2011 at 8:35 AM, Avi Kivity <address@hidden> wrote:
> On 09/14/2011 11:27 AM, Alexander Graf wrote:
>>
>> On 14.09.2011, at 10:24, Jan Kiszka wrote:
>>
>> >  On 2011-09-14 10:22, Avi Kivity wrote:
>> >>  On 09/14/2011 11:20 AM, Jan Kiszka wrote:
>> >>>>
>> >>>>  Anyway PCI supports the vga region at 0xa0000-0xc0000.  Where is it
>> >>>>  supposed to be mapped?
>> >>>
>> >>>  ...but not all PCI bridges make use of this feature / forward legacy
>> >>>  requests.
>> >>>
>> >>
>> >>  Then this should be fixed in the bridge?
>> >
>> >  Yes, it's a PPC bug.
>>
>> So how does the bridge not forward it then?
>>
>
> I expect that currently vga adds the region to pci_address_space().  We need
> to create a pci_address_space_vga() function that returns a region for vga
> to use.  Then add or remove the region to pci_address_space(), within the
> bridge code, depending on whether the bridge forwards vga accesses or not.

Similar treatment should be also needed for VGA IO ports 0x3b0 etc.

> (assuming I understood the problem correctly - not sure)

I think you did.