Hi, all ! As the "Understanding the Linux Kernel" says in Appendix A, when reset, CPU begin execution at physical address 0xFFFFFFF0. So in section2.5, the author says, the physical address range 0xFFFF0000-0xFFFFFFFF is mapped by the hardware to the BIOS's ROM chip . Appendix A also says BIOS uses Real Mode addresses, which can only address 1M space. If so, how does the CPU addresses 0xFFFF0000-0xFFFFFFFF? Some article said the BIOS was mapped at physical address range 0xF0000-0xFFFF, but article (in http://www.x86.org/productivity/a20reset.htm) said that the execution did begins at 0xFFFFFFF0. Would any people tell me the truth? Another question: when CPU in Read Mode, the A20 address line is disabled, isn't it? Thanks in advance! Regards, Cheng -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
