| /* |
| * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>. |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License as |
| * published by the Free Software Foundation; either version 2 of the |
| * License, or any later version. |
| * |
| * This program is distributed in the hope that it will be useful, but |
| * WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| * 02110-1301, USA. |
| * |
| * You can also choose to distribute this program under the terms of |
| * the Unmodified Binary Distribution Licence (as given in the file |
| * COPYING.UBDL), provided that you have satisfied its requirements. |
| */ |
| |
| FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ) |
| |
| /** @file |
| * |
| * Linux kernel prefix |
| * |
| */ |
| |
| .section ".note.GNU-stack", "", @progbits |
| .text |
| |
| /* Layout of kernel header */ |
| .struct 0 |
| hdr_code0: .space 4 |
| hdr_code1: .space 4 |
| hdr_text_offset: .space 8 |
| hdr_image_size: .space 8 |
| hdr_flags: .space 8 |
| hdr_version: .space 4 |
| hdr_res1: .space 4 |
| hdr_res2: .space 8 |
| hdr_magic: .space 8 |
| hdr_magic2: .space 4 |
| hdr_res3: .space 4 |
| hdr_end: |
| .org 64 |
| .previous |
| |
| /* Header version */ |
| #define HDR_VERSION( major, minor ) ( ( (major) << 16 ) | (minor) ) |
| #define HDR_VERSION_0_2 HDR_VERSION ( 0, 2 ) |
| |
| /* Header flags */ |
| #define HDR_FL_BIG_ENDIAN 0x00000001 |
| |
| /* Magic numbers */ |
| #define HDR_MAGIC "RISCV\0\0\0" |
| #define HDR_MAGIC2 "RSC\x05" |
| |
| /* |
| * Linux kernel header |
| */ |
| .section ".prefix", "ax", @progbits |
| |
| /* Executable code / MZ header (for EFI-compatible binaries) */ |
| .org hdr_code0 |
| j _lkrn_start |
| |
| /* Image load offset |
| * |
| * Must be set to the size of a single "megapage" (2MB for |
| * 64-bit, 4MB for 32-bit). |
| */ |
| .org hdr_text_offset |
| .dword _max_align |
| |
| /* Image size (including uninitialised-data potions) */ |
| .org hdr_image_size |
| .dword _memsz |
| |
| /* Flags */ |
| .org hdr_flags |
| .dword 0 |
| |
| /* Version */ |
| .org hdr_version |
| .word HDR_VERSION_0_2 |
| |
| /* Magic numbers */ |
| .org hdr_magic |
| .ascii HDR_MAGIC |
| .org hdr_magic2 |
| .ascii HDR_MAGIC2 |
| |
| .org hdr_end |
| |
| /* |
| * Linux kernel entry point |
| */ |
| .globl _lkrn_start |
| _lkrn_start: |
| /* Identify temporary page table and stack space |
| * |
| * Linux expects to be placed at the image load offset from |
| * the start of RAM. Assume that our loaded image is |
| * therefore already writable, and that we can therefore use |
| * the page table and stack within our (not yet zeroed) .bss |
| * section. |
| */ |
| la a2, page_table |
| la sp, _estack |
| |
| /* Install iPXE */ |
| call install |
| |
| /* Call main program */ |
| call main |
| |
| /* We have no return path, since the Linux kernel does not |
| * define that a valid return address exists. |
| * |
| * Attempt a system reset, since there is nothing else we can |
| * viably do at this point. |
| */ |
| j reset_system |
| .size _lkrn_start, . - _lkrn_start |
