| // Copyright 2020 The Fuchsia Authors |
| // |
| // Use of this source code is governed by a MIT-style |
| // license that can be found in the LICENSE file or at |
| // https://opensource.org/licenses/MIT |
| |
| #include <asm.h> |
| |
| // This header is generated from the symbol table of the linked kernel. |
| // It defines VERSION_STRING_OFFSET and VERSION_STRING_SIZE, which are the |
| // bounds of the embedded version string variable inside the kernel image. |
| #include "kernel-image.h" |
| |
| // This header defines VERSION_STRING_FILE for use below. It also defines |
| // VERSION_STRING_SIZE, not to the size of the file but to the maximum size to |
| // be allocated at compile time. This better match what kernel-image.h has |
| // extracted from the kernel symbol table, or something went wrong. That |
| // mismatch will cause a non-identical re-#define error at compile time. |
| #include <lib/version/version-string.h> |
| |
| // Pad out to the header size that was allocated in the kernel image layout. |
| // This ensures that the kernel image is aligned correctly in memory. |
| .org BOOT_HEADER_SIZE |
| |
| // Crack the kernel image in half around the version string and replace the |
| // wafer-thin layer in the middle with the contents of the separate version |
| // string file, which can change independently of the kernel image itself. |
| |
| .incbin KERNEL_IMAGE_FILE, BOOT_HEADER_SIZE, VERSION_STRING_OFFSET - BOOT_HEADER_SIZE |
| |
| // Exactly VERSION_STRING_SIZE bytes are to be replaced in the image. |
| 0: |
| .incbin VERSION_STRING_FILE |
| |
| // The replaced bytes must end with a NUL terminator. |
| .byte 0 |
| |
| // If it's smaller, pad the difference with more NULs. |
| 1: |
| .space VERSION_STRING_SIZE - (1b - 0b) |
| |
| // The second half of the kernel image skips the compile-time embedded string. |
| .incbin KERNEL_IMAGE_FILE, VERSION_STRING_OFFSET + VERSION_STRING_SIZE |
