diff options
Diffstat (limited to 'src/romlayout.S')
| -rw-r--r-- | src/romlayout.S | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/src/romlayout.S b/src/romlayout.S index 8125277..cbe6b1c 100644 --- a/src/romlayout.S +++ b/src/romlayout.S @@ -384,6 +384,56 @@ entry_elf: .code16gcc + EXPORTFUNC entry_csm +entry_csm: + // Backup register state + pushfw + cli + cld + pushl %eax // dummy + PUSHBREGS + + // Backup stack location and convert to a "flat pointer" + movl %ss, %ebx + movw %bx, BREGS_code+2(%esp) // Store %ss in bregs->code.seg + shll $4, %ebx + addl %esp, %ebx + + // Change to BUILD_STACK_ADDR stack + xorl %eax, %eax + movw %ax, %ss + movl $BUILD_STACK_ADDR, %esp + + // Jump to 32bit mode and call handle_csm(bregs) + movl $(1f + BUILD_BIOS_ADDR), %edx + jmp transition32 + .code32 +1: movl %ebx, %eax + calll _cfunc32flat_handle_csm - BUILD_BIOS_ADDR + movl $2f, %edx + jmp transition16big + + .global csm_return +csm_return: + movl %eax, %ebx + movl $2f, %edx + jmp transition16big + .code16gcc + + // Switch back to original stack +2: movzwl BREGS_code+2(%ebx), %eax + movl %eax, %ecx + shll $4, %ecx + subl %ecx, %ebx + movl %eax, %ss + movl %ebx, %esp + + // Restore register state and return. + POPBREGS + addw $4, %sp // pop dummy + popfw + lretw + /**************************************************************** * Interrupt entry points |