where is variable edata defined ?

The variable such as _edata, _etext,_gdt are defined in the file asnames.h(/usr/include/machine/asnames.h),but 1. Where is the file that the variable such as edata,etext,gdt are defined in? and 2. What's the file name? Thank you very much Fre Tre

question about boot code

1. I try to learn something about boot code with version 3.0. I wander whether I can begin with biosboot?(/usr/src/sys/i386/ boot/biosboot) 2. The initialized data will be loaded into memory after kernel text during boot stage. And where is the file that the initialized data is de

help about boot code

1. I try to learn something about boot code with version 3.0. I wander whether I can begin with biosboot?(/usr/src/sys/i386/boot/biosboot) 2. The intialized data will be loaded into memory after kernel text during boot stage, and where is the file that the initialized data is defined