Re: [PATCH 1/2] hw/mips/jazz: Use generic I/O bus via get_system_io()

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

On 3/11/21 5:21 PM, Philippe Mathieu-Daudé wrote:
> +Aspeed team
> 
> On 3/11/21 1:18 PM, Philippe Mathieu-Daudé wrote:
>> On 3/10/21 9:29 PM, Peter Xu wrote:
> 
>>> Yeah no worry - it's just that I feel one memory_region_init_alias() call is
>>> probably missing in your huge series somewhere, so that you'll take that alias
>>> MR as subregion rather than the real MR (which is the root of one AS).
>>
>> OK, with your earlier comments start + Mark other comment I start
>> to understand better.
>>
>> So far:
>>
>> (1a) AddressSpace is a physical view, its base address must be zero
>>
>> (1b) AddressSpace aperture is fixed (depends on hardware design,
>> not changeable at runtime
>>
>> Therefore due to (1a):
>> (2) AddressSpace root MemoryRegion is a container and must not be
>> mmio-mapped anywhere (in particular not on SysBus).
>>
>> (3) If hardware has a MMIO view of an AddressSpace, it has to be
>> via a MemoryRegion alias. That way the alias handles paddr offset
>> adjustment to the zero-based AddressSpace root container MR.
>> Aliasing allows resizing the alias size without modifying the AS
>> aperture size (1b).
>>
>> I'll start adding assertions for (1a) and (2) in the code base and
>> see if (3) adjustments are required.
> 
> So using:
> 
> -- >8 --
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index 874a8fccdee..8ce2d7f83b9 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -713,6 +713,12 @@ static MemoryRegion
> *memory_region_get_flatview_root(MemoryRegion *mr)
>                  continue;
>              }
>          }
> +        if (mr && mr->addr) {
> +            error_report("Detected flatview root memory region '%s' with"
> +                         " non-zero base address (0x%"HWADDR_PRIx"):
> aborting",
> +                         memory_region_name(mr), mr->addr);
> +            abort();
> +        }
> 
>          return mr;
>      }
> ---
> 
> I get:
> 
> $ ./qemu-system-arm -M ast2600-evb
> qemu-system-arm: Detected flatview root memory region
> 'aspeed.fmc-ast2600.flash' with non-zero base address (0x20000000): aborting
> Aborted (core dumped)

Another one (PPC):

$ ./qemu-system-ppc -S -monitor stdio -M 40p
QEMU 5.2.50 monitor - type 'help' for more information
(qemu) qemu-system-ppc: Detected flatview root memory region 'pci-io'
with non-zero base address (0x80000000): aborting
Aborted (core dumped)

$ ./qemu-system-ppc -S -monitor stdio -M 40p
QEMU 5.2.50 monitor - type 'help' for more information
(qemu) info mtree
address-space: raven-io
  0000000080000000-00000000bf7fffff (prio 0, i/o): pci-io
    0000000080000000-0000000080000007 (prio 0, i/o): dma-chan
    0000000080000008-000000008000000f (prio 0, i/o): dma-cont
    0000000080000020-0000000080000021 (prio 0, i/o): pic
    0000000080000040-0000000080000043 (prio 0, i/o): pit
    0000000080000060-0000000080000060 (prio 0, i/o): i8042-data
    0000000080000061-0000000080000061 (prio 0, i/o): pcspk
    0000000080000064-0000000080000064 (prio 0, i/o): i8042-cmd
    0000000080000070-0000000080000071 (prio 0, i/o): rtc
      0000000080000070-0000000080000070 (prio 0, i/o): rtc-index
    0000000080000074-0000000080000077 (prio 0, i/o): m48t59
    0000000080000081-0000000080000083 (prio 0, i/o): dma-page
    0000000080000087-0000000080000087 (prio 0, i/o): dma-page
    ...

address-space: lsi-pci-io
  0000000080000000-00000000bf7fffff (prio 0, i/o): pci-io
    0000000080000000-0000000080000007 (prio 0, i/o): dma-chan
    0000000080000008-000000008000000f (prio 0, i/o): dma-cont
    0000000080000020-0000000080000021 (prio 0, i/o): pic
    0000000080000040-0000000080000043 (prio 0, i/o): pit
    0000000080000060-0000000080000060 (prio 0, i/o): i8042-data
    0000000080000061-0000000080000061 (prio 0, i/o): pcspk
    0000000080000064-0000000080000064 (prio 0, i/o): i8042-cmd
    0000000080000070-0000000080000071 (prio 0, i/o): rtc
      0000000080000070-0000000080000070 (prio 0, i/o): rtc-index
      ...

memory-region: pci-memory
  00000000c0000000-00000000feffffff (prio 0, i/o): pci-memory
    00000000c00a0000-00000000c00bffff (prio 1, i/o): vga-lowmem