[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。
( O3 {$ c8 _0 ^4 z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。
7 f/ V6 j+ _% P; e4 u, T% O(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
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我的计算机用的是intel的ICH7南桥。
" h. [' T, T2 T在手册上
FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
$ L$ F( ?& a, d6 x: x7 m# MFWH_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
* Q! y- m4 h7 U; V3 w, `6 kFF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
7 U! I# C9 P7 _: @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
FF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
% l: v& G1 `' }5 S: s6 A. K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？
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5 t/ r4 ~, T  ]) m6 B  Y( A1 d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
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
7 L/ m: |" O# d1 }write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
) k4 P: _) A. ^% }6 f( d7 oa standby power state.
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" z2 K  T6 `" c& I1 d详见LPC spec:
& Z5 z! w3 Z; @3 W" [http://www.intel.com/design/chipsets/industry/25128901.pdf
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! P8 p" e0 O8 F3 {( Y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.