[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。
7 |$ B# |8 r/ L2 ~9 s2 r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。
" }! Q2 Z) G, x  Z4 A(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。
% d  q9 Y: A* r8 p' L' @( }1 D% K在手册上
FWH_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 C1 j; _8 @7 Y: _FF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
5 x. b, A  }% p+ x9 sFWH_DEC_EN1—Firmware Hub Decode Enable Register
  D, |+ {2 Z' _6 u7 a; I(LPC I/F—D31:F0)
) w" }* ^; E8 y' C; e. d2 ^FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
0 = Disable.
# d3 a) T8 n! T3 Q& D  R: R1 = Enable the following ranges for the Firmware Hub
FF70 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？
4 W7 b) ?1 o( b/ q7 K
; L7 ^2 s/ b* b- U谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
$ m' p! c7 e2 @  f8 {This one clock field is used to indicate which of multiple Firmware components is being selected.
  ]& s# |& L' KThe 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
( _: v9 ?9 a, j1 X+ iwrite. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
a standby power state.
7 H: _9 W+ @* f& Y0 g9 O# y3 j
详见LPC spec:
# B9 d8 a( }, E2 P& _% ^" V) m) Fhttp://www.intel.com/design/chipsets/industry/25128901.pdf
. z* E# Q0 e$ C' V. o
$ {3 W- T6 M% I9 y: \; V, G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.