[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。
( ]$ U+ k2 H. f* U+ F) O3 P(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
( I: K( Y0 b( U' _
5 _* ^: p' o0 [! w9 {" M" a# i我的计算机用的是intel的ICH7南桥。
在手册上
FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
' T# T( P- a% o. ^$ u" v+ [2 V8 WFWH_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
7 V5 I- q4 n( C) T! P1 MFF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
# j2 S' z, E8 l' s" ~(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
! v, Q: e/ ?/ k9 p' }, o1 q0 = Disable.
* @3 f- H* ]4 t4 u& I1 Y  K1 = Enable the following ranges for the Firmware Hub
5 r" u+ e/ i! _; J; E; j' zFF70 0000h – FF7F FFFFh
# o  d( a  s) O8 M  q% v& Y+ HFF30 0000h – FF3F FFFFh
- g! m. R7 k% Z1 H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),
. q& h7 ]8 n8 a0 M/ Z( yThis 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
# g3 I' d5 @" H( Opins on the Firmware component. If there is a match, the Firmware component will continue to
8 e- ~; T5 P- O3 F! Bdecode the cycle to determine which bytes are requested on a read or which bytes to update on a
2 ]$ V8 V8 [7 N% ]$ E, `' Y! ~write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
+ h7 ^; J: i/ c2 U. `a standby power state.
8 M5 Z* L' v+ W: R5 ?1 H
5 T9 }4 T  O' R( d! Q6 V) G+ b$ e: q1 M详见LPC spec:
) T" ^# j! e6 m& ahttp://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.