[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。
: b/ t/ Q- G4 e- a% b6 s- ~(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。
在手册上
! c! f" \% y2 Z5 _" x) gFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
# E# w" c* |, T9 sFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
; z+ i4 p4 v! z# yThe IDSEL programmed in this field addresses the following memory ranges:
2 I) v: x  m9 s" r; {7 }/ zFF70 0000h – FF7F FFFFh
1 M7 _( s5 c: L! b8 D2 L! l" Y; dFF30 0000h – FF3F FFFFh
, T8 m3 u/ S. U7 e, s# w在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
6 s! v5 f& _2 \, e, @; T9 s(LPC I/F—D31:F0)
+ X7 p9 P7 e5 [) J" N9 cFWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
3 |5 Z7 u$ J3 o9 a2 |0 = Disable.
1 = Enable the following ranges for the Firmware Hub
$ b# j8 U9 U$ a. v" x5 C' n4 yFF70 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？
5 g  t/ u! w2 B4 p: K8 B9 p
谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
4 A) G  k- d# k* j2 t9 I! XThis 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
pins on the Firmware component. If there is a match, the Firmware component will continue to
6 D  Q5 r% J2 \' _decode the cycle to determine which bytes are requested on a read or which bytes to update on a
9 [7 _0 l. I1 L1 c' bwrite. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
/ V: m5 J* S; P( p9 Oa standby power state.

详见LPC spec:
  Z! |& [+ d  B: dhttp://www.intel.com/design/chipsets/industry/25128901.pdf
2 g; J5 g. b4 _. G8 `0 Q: T
  ]. L7 u( ^- q0 r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.