[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)
3 V# l9 {0 Y- ]& S  M: O$ L- }
6 k, G; n3 L5 }4 I: ~7 ~' b5 i  r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)
& O' v7 M, O% m" V7 H$ \; a# CFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
) M) @7 P2 Z; T8 s% W5 bThe IDSEL programmed in this field addresses the following memory ranges:
FF70 0000h – FF7F FFFFh
6 `3 U/ c2 O8 I; A" BFF30 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.
/ N4 g9 C/ q- H5 I: @0 = Disable.
: [1 f# F4 J% Y3 @9 E1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
6 N. k4 [5 l9 b0 \) G/ DFF30 0000h – FF3F FFFFh
  A! |! A3 ^) l* p; [3 U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？
/ l9 _4 U4 A: {! P9 m$ x
1 H/ ~' B4 Z. R$ x2 G. j& m3 m谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
, T0 D, p6 S7 S1 g. T7 _& qThis one clock field is used to indicate which of multiple Firmware components is being selected.
+ E2 F$ h4 z# b* A3 tThe 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
4 M+ L1 O5 N% S) [9 F. {write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
a standby power state.
7 R, b+ I8 d& P, S
详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf

5 L) G1 `. S7 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.