[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)
2 w8 n  ?" Q3 Y% c6 l5 }
我的计算机用的是intel的ICH7南桥。
在手册上
FWH_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.
6 i6 `. u1 [5 vThe IDSEL programmed in this field addresses the following memory ranges:
FF70 0000h – FF7F FFFFh
! a9 `/ O( T8 a2 P9 k  pFF30 0000h – FF3F FFFFh
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.
0 = Disable.
1 = Enable the following ranges for the Firmware Hub
$ `* g% ?( G9 ]% iFF70 0000h – FF7F FFFFh
FF30 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？

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.
4 J& H, G. }7 \/ F9 W! YThe 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
/ S; g! q+ A9 Y, h1 Idecode 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
* W3 @: c( U  Ma standby power state.

详见LPC spec:
$ r& H. v4 [$ c: F1 m$ X- A. Lhttp://www.intel.com/design/chipsets/industry/25128901.pdf

8 ]! J2 c7 e9 Z1 [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.