Re: [PATCH v2 4/9] target/hppa: Fix PDC address translation on PA2.0 with PSW.W=0

[Helge Deller <deller@gmx.de>]

On 1/9/24 10:14, Richard Henderson wrote:
> On 1/8/24 00:22, deller@kernel.org wrote:
>> From: Helge Deller <deller@gmx.de>
>>
>> Fix the address translation for PDC space on PA2.0 if PSW.W=0.
>> Basically, for any address in the 32-bit PDC range from 0xf0000000 to
>> 0xf1000000 keep the lower 32-bits and just set the upper 32-bits to
>> 0xfffffff0.
>>
>> This mapping fixes the emulated power button in PDC space for 32- and
>> 64-bit machines and is how the physical C3700 machine seems to map
>> PDC.
>>
>> Signed-off-by: Helge Deller <deller@gmx.de>
>> ---
>>   target/hppa/mem_helper.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/target/hppa/mem_helper.c b/target/hppa/mem_helper.c
>> index 08abd1a9f9..011b192406 100644
>> --- a/target/hppa/mem_helper.c
>> +++ b/target/hppa/mem_helper.c
>> @@ -56,7 +56,7 @@ hwaddr hppa_abs_to_phys_pa2_w0(vaddr addr)
>>           addr = (int32_t)addr;
>>       } else {
>>           /* PDC address space */
>> -        addr &= MAKE_64BIT_MASK(0, 24);
>> +        addr = (uint32_t)addr;
>>           addr |= -1ull << (TARGET_PHYS_ADDR_SPACE_BITS - 4);
>>       }
>>       return addr;
>
> I believe this to be incorrect, as it contradicts Figures H-10 and H-11.

Yes, but that seems to be how it's really implemented on physical hardware.
We have seen other figures as well, which didn't reflect the real world either.
IMHO we can revert if it really turns out to be wrong and when we
get a better solution.

Helge