[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。
4 f( j4 l* [& E9 d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。
7 a( K8 W: _7 A3 n# t  ~(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)

% x1 z) j7 o3 _0 C我的计算机用的是intel的ICH7南桥。
在手册上
5 [& Y- G" u4 D/ R+ |FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
  G4 M+ r; ^8 WFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
* J' D# E! o6 z) b9 f" M- {$ KThe IDSEL programmed in this field addresses the following memory ranges:
FF70 0000h – FF7F FFFFh
2 B% g4 n# F) E. J. \FF30 0000h – FF3F FFFFh
3 d) m; S4 R! T. o: x/ b  ~在这里 IDSEL 如何理解。
/ j: E2 i1 u3 j! ~2 h* iFWH_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.
; h) g+ G3 }' ?6 u4 F6 U0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
1 [+ S- F  E' P! T* }7 G7 D' UFF30 0000h – FF3F FFFFh
  k9 Z& u! S; G* w4 Q$ n/ H4 n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？
% g, H' a# [7 B8 p
谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
. c6 b( Q2 {" ]; C' rThis one clock field is used to indicate which of multiple Firmware components is being selected.
- W: ?- o, o& {+ _/ {9 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
decode 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
5 z* X$ d1 M- ]a standby power state.

& D! W, c. Z) ?, y, E2 j% {详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf

" V% K/ D+ t# F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.