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

[Philippe Mathieu-Daudé]

On 3/10/21 8:49 PM, Peter Xu wrote:
> On Wed, Mar 10, 2021 at 08:12:54PM +0100, Philippe Mathieu-Daudé wrote:
>> No need to create a local ISA I/O MemoryRegion, use get_system_io().
>>
>> This partly reverts commit 5c63bcf7501527b844f61624957bdba254d75bfc.
> 
> I think it's not a clean revert of that, see below.
> 
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>  hw/mips/jazz.c | 6 ++----
>>  1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/mips/jazz.c b/hw/mips/jazz.c
>> index 1a0888a0fd5..9ac9361b7eb 100644
>> --- a/hw/mips/jazz.c
>> +++ b/hw/mips/jazz.c
>> @@ -158,7 +158,6 @@ static void mips_jazz_init(MachineState *machine,
>>      rc4030_dma *dmas;
>>      IOMMUMemoryRegion *rc4030_dma_mr;
>>      MemoryRegion *isa_mem = g_new(MemoryRegion, 1);
>> -    MemoryRegion *isa_io = g_new(MemoryRegion, 1);
>>      MemoryRegion *rtc = g_new(MemoryRegion, 1);
>>      MemoryRegion *i8042 = g_new(MemoryRegion, 1);
>>      MemoryRegion *dma_dummy = g_new(MemoryRegion, 1);
>> @@ -259,11 +258,10 @@ static void mips_jazz_init(MachineState *machine,
>>      memory_region_add_subregion(address_space, 0x8000d000, dma_dummy);
>>  
>>      /* ISA bus: IO space at 0x90000000, mem space at 0x91000000 */
>> -    memory_region_init(isa_io, NULL, "isa-io", 0x00010000);
>>      memory_region_init(isa_mem, NULL, "isa-mem", 0x01000000);
>> -    memory_region_add_subregion(address_space, 0x90000000, isa_io);
>> +    memory_region_add_subregion(address_space, 0x90000000, get_system_io());
> 
> The old code has an alias created just for adding subregion into 
> address_space:
> 
> -    /* ISA IO space at 0x90000000 */
> -    memory_region_init_alias(isa, NULL, "isa_mmio",
> -                             get_system_io(), 0, 0x01000000);
> -    memory_region_add_subregion(address_space, 0x90000000, isa);
> -    isa_mem_base = 0x11000000;
> 
> While you didn't revert that part.  Maybe that's the issue?

Hmm I'll have a look. This is not the series I'm working on, which
is much bigger and not ready for posting yet. I simply looked for
something similar (a bus mapped into sysbus) and remembered the
ISA bus from Jazz machines. I'll see if I can find a better PoC.

Thanks for having a look at this patch,

Phil.