|
From: | Alexander Graf |
Subject: | Re: [Qemu-devel] Support NEC PC-98x1 on QEMU |
Date: | Tue, 8 Sep 2009 16:36:04 +0200 |
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 resetedthey are masked.Now A20 gate is hard-corded in i386 core, but it is only PC/AT specificationsprobably 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
[Prev in Thread] | Current Thread | [Next in Thread] |