[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)

0 [- n3 R( S: S& U" |我的计算机用的是intel的ICH7南桥。
1 }6 V& \6 U# r$ P在手册上
' D$ {& q7 M' ^FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
3 }  I2 a! P: K" f# t+ g9 ?7 g( ZFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
6 y. ?( `0 s% Z9 E7 AThe IDSEL programmed in this field addresses the following memory ranges:
FF70 0000h – FF7F FFFFh
% j' P+ H+ X4 I0 c! g1 |FF30 0000h – FF3F FFFFh
: O: T- v4 {* g0 r2 r在这里 IDSEL 如何理解。
7 [% S6 h0 W9 t. HFWH_DEC_EN1—Firmware Hub Decode Enable Register
! G+ T) ~1 j" j( k(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
. D' p, a6 b$ X  |/ e1 i* m: T* kFF70 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？
# C2 b5 m2 \" K: H7 \
9 s7 `8 S5 s* v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.
( ]; u2 c4 @, r: {! s+ }The 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
a standby power state.

详见LPC spec:
% i+ h7 M9 N% H% |% h. [( h8 shttp://www.intel.com/design/chipsets/industry/25128901.pdf

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.