Re: [Qemu-devel] [PATCH 00/28] Memory API for 1.6: fix I/O port endianness mess

[Paolo Bonzini <pbonzini@redhat.com>]

Il 22/07/2013 17:04, Peter Maydell ha scritto:
> On 22 July 2013 15:36, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Il 22/07/2013 16:32, Peter Maydell ha scritto:
>>> In the long term it would be good to identify which boards
>>> were using isa_mmio purely for the benefit of old_portio
>>> (which I think is basically "boards where the CPU has no
>>> concept of port I/O instructions").
>>
>> All of them.  Only i386/x86_64 has I/O space, as far as I know.
> 
> Sounds plausible. I had wondered if our ISA bus infrastructure
> assumed that ISA device IO ports live in the system IO space,
> but it doesn't.

No, luckily it doesn't, and neither should the PCI-to-ISA bridges as you
found out---they do not after these patches.  PReP is an exception, but
I think it could be rewritten to use an IOMMU memory region.

> Side question: should the ICH9 emulation ich9_lpc_initfn()
> really put its ISA bus in the system IO space rather than
> in the pci_address_space_io() ?

No, I think it should use pci_address_space_io().  PCI devices (the ISA
bridge is one) should not know that a system IO space exists, only the
PCI host bridge has that knowledge.

Paolo