ref: f40225e86cf4b92cab975d9121ff06ed5cfe9d91
dir: /sys/src/9/pc/rebootcode.s/
#include "mem.h" /* * Turn off MMU, then memmove the new kernel to its correct location * in physical memory. Then jumps the to start of the kernel. */ TEXT main(SB),$0 MOVL p1+0(FP), DI /* destination */ MOVL DI, AX /* entry point */ MOVL p2+4(FP), SI /* source */ MOVL n+8(FP), CX /* byte count */ /* * disable paging */ MOVL CR0, DX ANDL $~0x80000000, DX /* ~(PG) */ MOVL DX, CR0 MOVL $0, DX MOVL DX, CR3 /* stack below entry point */ MOVL AX, SP /* park cpu for zero entry point */ ORL AX, AX JZ _idle /* * the source and destination may overlap. * determine whether to copy forward or backwards */ CMPL SI, DI JGT _forward MOVL SI, DX ADDL CX, DX CMPL DX, DI JGT _back _forward: CLD REP; MOVSB JMP _startkernel _back: ADDL CX, DI ADDL CX, SI SUBL $1, DI SUBL $1, SI STD REP; MOVSB JMP _startkernel /* * JMP to kernel entry point. Note the true kernel entry point is * the virtual address KZERO|AX, but this must wait until * the MMU is enabled by the kernel in l.s */ _startkernel: ORL AX, AX /* NOP: avoid link bug */ JMP* AX _idle: HLT JMP _idle