[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。
" a7 `1 D0 r* K+ ?! z(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)

4 W: ?; \" c! Z4 n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)
2 l' z; G! k! Q. `FWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
) ^8 _0 y  z2 o) iThe IDSEL programmed in this field addresses the following memory ranges:
& }. m: i) S( |( G. \1 z, AFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
  d% z" d/ Z: s( _FWH_DEC_EN1—Firmware Hub Decode Enable Register
) E( y# p+ u0 G(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
9 l+ _: @: I1 Q0 = Disable.
0 A2 W5 v; |$ @% e1 = Enable the following ranges for the Firmware Hub
/ b/ L& P+ o( H( J7 }FF70 0000h – FF7F FFFFh
" T' q6 B" ~4 D/ j( z( Z9 Z" {FF30 0000h – FF3F FFFFh
1 B# m: ~% K. w/ n1 I2 z- Z. X  o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？
: Z& E- K1 |1 T6 Y5 L8 x
谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
4 M) k1 b6 b- S! Q  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
9 P! F! `( p. ~: r3 g3 vpins on the Firmware component. If there is a match, the Firmware component will continue to
# r. ^2 e! y9 u/ Ndecode 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
5 \* `. i/ B5 [! a# G; ua standby power state.

  g" {$ c+ \" \7 B& Z详见LPC spec:
5 X4 }3 z% q# y3 v* Fhttp://www.intel.com/design/chipsets/industry/25128901.pdf

: b6 w' g- `5 w3 }$ `! b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.