Re: [Qemu-devel] [PATCH 3/3] target-xtensa: xtfpga: support noMMU cores

[Max Filippov]

On Thu, Oct 1, 2015 at 1:23 AM, Peter Crosthwaite
<address@hidden> wrote:
> On Wed, Sep 30, 2015 at 3:07 PM, Max Filippov <address@hidden> wrote:
>> On Thu, Oct 1, 2015 at 12:02 AM, Peter Crosthwaite
>> <address@hidden> wrote:
>>> Which makes MMU vs noMMU a board level property, not a CPU property.
>>> It should appear in QEMU as such.
>>
>> Ok, one last try: can this property be queried from the selected CPU
>> and passed to SoC initialization code?
>
> No, what I am trying to say is go the other way round. The property is
> on the SoC, and it is used to select the CPU type.

This is not what happens in reality. In reality the MMU type is the
CPU property.
A set of CPU properties comes from the outside along with the CPU name, and
that's the only possible set of properties for this name.
XTFPGA bitstream build scripts lay out its address space based on MMU
type of the selected CPU.

So let's make XTFPGA an SoC with a property that selects its address space
layout. The machine (lx60/lx200/ml605/kc705) is configured with a CPU, it
queries MMU type from it and instantiates XTFPGA SoC with proper address
space. That seems to be closest to what happens in reality.

-- 
Thanks.
-- Max