Re: [Qemu-ppc] [Qemu-devel] [PATCH 2/2] m48t59: add mem_base value to m48t59_init_isa()

[Mark Cave-Ayland]

On 19/01/15 15:04, Peter Maydell wrote:

> On 19 January 2015 at 12:57, Artyom Tarasenko <address@hidden> wrote:
>> But out of curiosity, would it be possible to have a sysbus device
>> somewhere in a middle of PCI space? Do sysbus devices have higher
>> priority if the address spaces overlap? Or do you mean that the PCI
>> controller needs to be modified to have a hole for a sysbus device?
> 
> You can specify the priority when you map devices into a MemoryRegion,
> so you can handle this by either making the sysbus device a positive
> priority or by making the PCI window have a negative priority.
> 
> (We don't actually get this right on x86 currently,
> which has resulted in some awkwardness for the PPC desire to
> make PCI address 0 valid.)

I'm not sure this would work for SPARC64 since potentially OpenBIOS can
program the I/O BAR for the ebus anywhere (and the NVRAM is located on
the ebus). At the moment we cheat by creating an alias to I/O space at
the top of memory so that OpenBIOS can always access it at a fixed address.


ATB,

Mark.