[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。
# v7 y2 k7 T! }( W(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)

我的计算机用的是intel的ICH7南桥。
. [8 b7 t" }4 ^( x3 t在手册上
/ f0 J0 M$ d  M3 D" X2 Q9 J4 X2 `& tFWH_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:
FF70 0000h – FF7F FFFFh
6 c0 s9 R$ E, F. G- NFF30 0000h – FF3F FFFFh
: K2 s6 z- ~2 h! J在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
1 ]/ f6 |  ^' ^, m4 t. G+ n(LPC I/F—D31:F0)
, q8 B: e. ~% f: xFWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
0 = Disable.
; F) `. |3 m" Q$ h0 [1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
0 u  w/ h5 G0 U0 J$ ^4 l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？
0 ~* x) q1 y3 x" n) l6 t8 U
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.
The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
. M) \9 W, L( ?' }4 ?+ ?% mpins 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
5 i1 ?1 h& z2 ~: xwrite. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
4 |+ l6 a  E. F) A, ?% r. Wa standby power state.
; p) Y1 }, ^) x/ M7 `) R
详见LPC spec:
% @: X+ x. B: \; H& I* Khttp://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.