Re: [Qemu-devel] Support NEC PC-98x1 on QEMU

[武田 俊也]

Dear Alexander and Stuart,

Thank you very much for your comment.
I understand qemu implements rule and I agree with your opinion.

I modified my patch based on the codes received from git yesterday.
Please refer the attached archive.

-M pc98 and -M pc98pci are added to TARGET_I386.
-M isapc causes crash on windows now, and -M pc98 is same.
-M pc98pci is okay.

I added private_features to i386 for any features not defined in cpuid,
and I defined a20mask feature on it.

Thanks,
TAKEDA, toshiya

>On 08.09.2009, at 11:41, 武田 俊也 wrote:
>
>> Dear Stuart,
>>
>>> There's no need to add this as a whole new architecture, although
>>> perhaps the use of TARGET_PC98 was only meant to be temporary...
>>
>> The problem is that now TARGET_I386 is used for both 2 meanings,
>> cpu is i386 and the arch is PC/AT.
>
>No, that's what the -M switch is there for. Admittedly x86 has rather  
>few machine descriptions, but PC-98 really is just a "non-PC/AT"  
>machine, so it belongs there.
>
>[...]
>
>> About A20 line gate:
>>
>> In PC/AT arch, only A20 line is masked and when cpu is reseted it is  
>> not masked.
>> You know, In PC-98x1 arch, A20 and upper lines are masked and when  
>> cpu is reseted
>> they are masked.
>>
>> Now A20 gate is hard-corded in i386 core, but it is only PC/AT  
>> specifications
>> probably by external circuts, not cpu internal.
>> It may be possibly better to move a20 gate codes to pc.c and pc98.c,
>> but I think it is allowable to keep them in cpu core with #ifdef for  
>> each arch.
>
>Sounds like that should be a config variable in the CPU description,  
>so you can set the default CPU be "486,+a20mask" or so.
>
>In general, all the changes should be runtime variable dependent, so  
>the same binary can run PC/AT and PC-98.
>
>Alex
>
>
>

20090909-pc9821.tar.gz
Description: GNU Zip compressed data