| FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ) |
| |
| #include <librm.h> |
| |
| #define BZI_LOAD_HIGH_ADDR 0x100000 |
| |
| .text |
| .arch i386 |
| .code16 |
| .section ".prefix", "ax", @progbits |
| .globl _lkrn_start |
| _lkrn_start: |
| |
| /***************************************************************************** |
| * |
| * Kernel header |
| * |
| * We place our prefix (i.e. our .prefix and .text16.early sections) |
| * within the bzImage real-mode portion which gets loaded at |
| * 1000:0000, and our payload (i.e. everything else) within the |
| * bzImage protected-mode portion which gets loaded at 0x100000 |
| * upwards. |
| * |
| */ |
| |
| .org 0x1f1 |
| setup_sects: |
| .byte -1 /* Allow for initial "boot sector" */ |
| .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */ |
| .ascii "ADHL" |
| .long setup_sects |
| .long 512 |
| .long 0 |
| .previous |
| root_flags: |
| .word 0 |
| syssize: |
| .long 0 |
| .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */ |
| .ascii "ADPL" |
| .long syssize |
| .long 16 |
| .long 0 |
| .previous |
| ram_size: |
| .word 0 |
| vid_mode: |
| .word 0 |
| root_dev: |
| .word 0 |
| boot_flag: |
| .word 0xaa55 |
| jump: |
| /* Manually specify a two-byte jmp instruction here rather |
| * than leaving it up to the assembler. |
| */ |
| .byte 0xeb, ( setup - header ) |
| header: |
| .byte 'H', 'd', 'r', 'S' |
| version: |
| .word 0x0207 /* 2.07 */ |
| realmode_swtch: |
| .long 0 |
| start_sys: |
| .word 0 |
| kernel_version: |
| .word version_string - 0x200 |
| type_of_loader: |
| .byte 0 |
| loadflags: |
| .byte 0x01 /* LOADED_HIGH */ |
| setup_move_size: |
| .word 0 |
| code32_start: |
| .long 0 |
| ramdisk_image: |
| .long 0 |
| ramdisk_size: |
| .long 0 |
| bootsect_kludge: |
| .long 0 |
| heap_end_ptr: |
| .word 0 |
| ext_loader_ver: |
| .byte 0 |
| ext_loader_type: |
| .byte 0 |
| cmd_line_ptr: |
| .long 0 |
| initrd_addr_max: |
| .long 0xffffffff |
| kernel_alignment: |
| .long 0 |
| relocatable_kernel: |
| .byte 0 |
| min_alignment: |
| .byte 0 |
| xloadflags: |
| .word 0 |
| cmdline_size: |
| .long 0x7ff |
| hardware_subarch: |
| .long 0 |
| hardware_subarch_data: |
| .byte 0, 0, 0, 0, 0, 0, 0, 0 |
| |
| version_string: |
| .asciz VERSION |
| |
| /***************************************************************************** |
| * |
| * Setup code |
| * |
| */ |
| |
| setup: |
| /* Fix up code segment */ |
| pushw %ds |
| pushw $1f |
| lret |
| 1: |
| /* Set up stack just below 0x7c00 and clear direction flag */ |
| xorw %ax, %ax |
| movw %ax, %ss |
| movw $0x7c00, %sp |
| cld |
| |
| /* Retrieve command-line pointer */ |
| movl cmd_line_ptr, %edx |
| testl %edx, %edx |
| jz no_cmd_line |
| |
| /* Set up %es:%di to point to command line */ |
| movl %edx, %edi |
| andl $0xf, %edi |
| rorl $4, %edx |
| movw %dx, %es |
| |
| /* Find length of command line */ |
| pushw %di |
| movw $0xffff, %cx |
| repnz scasb |
| notw %cx |
| popw %si |
| |
| /* Make space for command line on stack */ |
| movw %sp, %di |
| subw %cx, %di |
| andw $~0xf, %di |
| movw %di, %sp |
| |
| /* Copy command line to stack */ |
| pushw %ds |
| pushw %es |
| popw %ds |
| pushw %ss |
| popw %es |
| rep movsb |
| popw %ds |
| |
| /* Store new command-line pointer */ |
| movzwl %sp, %edx |
| no_cmd_line: |
| |
| /* Calculate maximum relocation address */ |
| movl ramdisk_image, %ebp |
| testl %ebp, %ebp |
| jnz 1f |
| orl $0xffffffff, %ebp /* Allow arbitrary relocation if no initrd */ |
| 1: |
| /* Install iPXE */ |
| call alloc_basemem |
| xorl %esi, %esi |
| xorl %edi, %edi |
| call install_prealloc |
| |
| /* Set up real-mode stack */ |
| movw %bx, %ss |
| movw $_estack16, %sp |
| |
| /* Jump to .text16 segment */ |
| pushw %ax |
| pushw $1f |
| lret |
| .section ".text16", "awx", @progbits |
| 1: |
| /* Retrieve initrd pointer and size */ |
| movl ramdisk_image, %ebp |
| movl ramdisk_size, %ecx |
| |
| /* Set up %ds for access to .data16 */ |
| movw %bx, %ds |
| |
| /* Store command-line pointer */ |
| movl %edx, cmdline_phys |
| |
| /* Store initrd pointer and size */ |
| movl %ebp, initrd_phys |
| movl %ecx, initrd_len |
| |
| /* Run iPXE */ |
| virtcall main |
| |
| /* Uninstall iPXE */ |
| call uninstall |
| |
| /* Boot next device */ |
| int $0x18 |
| |
| /***************************************************************************** |
| * |
| * Open payload (called by libprefix) |
| * |
| * Parameters: |
| * %ds:0000 : Prefix |
| * %esi : Buffer for copy of image source (or zero if no buffer available) |
| * %ecx : Expected offset within buffer of first payload block |
| * Returns: |
| * %esi : Valid image source address (buffered or unbuffered) |
| * %ecx : Actual offset within buffer of first payload block |
| * CF set on error |
| */ |
| |
| .section ".text16.early", "awx", @progbits |
| .globl open_payload |
| open_payload: |
| |
| /* Our payload will always end up at BZI_LOAD_HIGH_ADDR */ |
| movl $BZI_LOAD_HIGH_ADDR, %esi |
| xorl %ecx, %ecx |
| lret |
| |
| /* Payload must be aligned to a whole number of setup sectors */ |
| .globl _payload_align |
| .equ _payload_align, 512 |
