[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。
8 a; q) y; q" l  ?1 L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。
6 d5 w, @/ [4 D1 r! B(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
; k) o# f; J3 ^/ o1 |/ SFWH_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
FF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
  j- y7 v, A8 S5 v8 g; S6 P(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
& \- f$ K% S  A- |0 = Disable.
" ]  A$ k$ G$ Z& c1 = Enable the following ranges for the Firmware Hub
, V% R4 P8 P2 [' q# ~* T. H/ IFF70 0000h – FF7F FFFFh
! h; v, j: x6 m. T! ZFF30 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？

谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
# m1 ]! v1 O+ `% O9 OThis 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
" ?+ t; r1 j! ^; x3 g/ l& _: x! tpins 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:
- ~, j+ }! J0 bhttp://www.intel.com/design/chipsets/industry/25128901.pdf
- ^' P, P! V5 f* j
* s: a5 `7 c& i$ K+ ~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.