[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
; m4 ^0 P: h  N$ x
我的计算机用的是intel的ICH7南桥。
% W" A# M' m) Y! x/ g% q在手册上
7 }$ R! f* k8 e1 r: A: G. f" S% L/ l& WFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
FWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
The IDSEL programmed in this field addresses the following memory ranges:
2 i) U* F) x! h( jFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
2 S* z- p! w7 t) z2 |在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
9 @. C( c9 }; g& f0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
; @1 q" j' ~# N: VFF30 0000h – FF3F FFFFh
除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？
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. K4 ]+ x* ]' G) s  B6 x谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
This one clock field is used to indicate which of multiple Firmware components is being selected.
! |, Y0 c: Y7 R/ j' v- y* jThe four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
pins on the Firmware component. If there is a match, the Firmware component will continue to
* e6 X2 C# ~4 M( H$ @3 v& ?! wdecode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
a standby power state.

1 e( T+ _  b  n详见LPC spec:
' C9 [0 t7 P. j2 U0 Zhttp://www.intel.com/design/chipsets/industry/25128901.pdf
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在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.