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

[Alexander Graf]

On 14.09.2011, at 22:06, Blue Swirl wrote:

> 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.

Well I don't completely, so would anybody who feels reasonably savvy in messing 
with the new memory api like to step up and implement this? :)


Alex