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https://github.com/fosslinux/live-bootstrap.git
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c748766fac
This is needed to make the monitoring/recovery shell on tty2 work, as the default console is tty0, which will just print to whichever virtual console is active at the moment, making the shell unusable.
230 lines
8.7 KiB
C
230 lines
8.7 KiB
C
/* SPDX-FileCopyrightText: 2023 Richard Masters <grick23@gmail.com> */
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/* SPDX-License-Identifier: MIT */
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "multiboot1.h"
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#define MULTIBOOT_MAGIC 0x2BADB002
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#define INITRD_MB 1280
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#define KEXEC_MB 256
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int main() {
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/* Read the kernel */
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printf("kexec-fiwix: starting...\n\n");
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FILE *fiwix_file = fopen("/boot/fiwix", "r");
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fseek(fiwix_file, 0, SEEK_END);
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int fiwix_len = ftell(fiwix_file);
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printf("kexec-fiwix: Fiwix kernel file length: %d\n", fiwix_len);
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puts("kexec-fiwix: Reading kernel...");
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fseek(fiwix_file, 0, SEEK_SET);
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char * fiwix_mem = malloc(fiwix_len);
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int read_len = fread(fiwix_mem, fiwix_len, 1, fiwix_file);
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fclose(fiwix_file);
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if (read_len < 1) {
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printf("kexec-fiwix: kernel fread error: %d\n", read_len);
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return EXIT_FAILURE;
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}
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/* Display info from ELF header */
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unsigned int e_entry = *((unsigned int *) (&fiwix_mem[0x18]));
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printf("ELF virtual entry point : 0x%x\n", e_entry);
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unsigned int e_phoff = *((unsigned int *) (&fiwix_mem[0x1C]));
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printf("ELF program header offset : 0x%x\n", e_phoff);
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unsigned int e_phnum = *((unsigned int *) (&fiwix_mem[0x2C]));
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e_phnum &= 0xFFFF;
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printf("ELF number of program headers: %d\n", e_phnum);
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unsigned int e_phentsize = *((unsigned int *) (&fiwix_mem[0x2A]));
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e_phentsize &= 0xFFFF;
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printf("ELF size of program headers : %d\n", e_phentsize);
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/* Load the kernel */
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puts("kexec-fiwix: Placing kernel in memory...");
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int header_num;
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for (header_num = 0; header_num < e_phnum; header_num++) {
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char * fiwix_prog_header = &fiwix_mem[e_phoff + header_num * e_phentsize];
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unsigned int p_offset = *((unsigned int *) (&fiwix_prog_header[0x04]));
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unsigned int p_vaddr = *((unsigned int *) (&fiwix_prog_header[0x08]));
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unsigned int p_paddr = *((unsigned int *) (&fiwix_prog_header[0x0C]));
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unsigned int p_filesz = *((unsigned int *) (&fiwix_prog_header[0x10]));
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unsigned int p_memsz = *((unsigned int *) (&fiwix_prog_header[0x14]));
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if (header_num == 0) {
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e_entry -= (p_vaddr - p_paddr);
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printf("ELF physical entry point : 0x%x\n", e_entry);
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}
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printf("header %d:\n", header_num);
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printf(" p_offset: 0x%08x\n", p_offset);
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printf(" p_paddr : 0x%08x\n", p_paddr);
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printf(" p_filesz: 0x%08x\n", p_filesz);
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printf(" p_memsz : 0x%08x\n", p_memsz);
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memset((void *)p_paddr, 0, p_memsz + 0x10000);
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memcpy((void *)p_paddr, &fiwix_mem[p_offset], p_filesz);
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}
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puts("Preparing multiboot info for kernel...");
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char cmdline[256];
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/* Don't use a serial console if configured for bare metal */
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char *bare_metal = getenv("BARE_METAL");
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if (bare_metal != NULL && strcmp(bare_metal, "True") == 0)
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{
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sprintf(cmdline, "fiwix console=/dev/tty1 root=/dev/ram0 ramdisksize=%d initrd=fiwix.ext2 kexec_proto=linux kexec_size=%d kexec_cmdline=\"init=/init consoleblank=0\"", INITRD_MB * 1024, KEXEC_MB * 1024);
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}
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else
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{
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sprintf(cmdline, "fiwix console=/dev/ttyS0 root=/dev/ram0 ramdisksize=%d initrd=fiwix.ext2 kexec_proto=linux kexec_size=%d kexec_cmdline=\"init=/init console=ttyS0\"", INITRD_MB * 1024, KEXEC_MB * 1024);
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}
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char * boot_loader_name = "kexec-fiwix";
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unsigned int next_avail_mem = 0x9800;
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multiboot_info_t * pmultiboot_info = (multiboot_info_t *) next_avail_mem;
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memset(pmultiboot_info, 0, sizeof(multiboot_info_t));
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pmultiboot_info->flags = MULTIBOOT_INFO_BOOT_LOADER_NAME
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| MULTIBOOT_INFO_MEMORY
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| MULTIBOOT_INFO_CMDLINE
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| MULTIBOOT_INFO_MODS
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| MULTIBOOT_INFO_MEM_MAP;
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next_avail_mem += sizeof(multiboot_info_t);
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pmultiboot_info->mem_lower = 0x0000027F;
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pmultiboot_info->mem_upper = 0x002FFB80;
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/* Set command line */
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pmultiboot_info->cmdline = next_avail_mem;
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strcpy((char *) next_avail_mem, cmdline);
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next_avail_mem += (strlen(cmdline) + 1);
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/* Set ramdrive info */
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pmultiboot_info->mods_count = 1;
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pmultiboot_info->mods_addr = next_avail_mem;
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multiboot_module_t *pmultiboot_module = (multiboot_module_t *) next_avail_mem;
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pmultiboot_module->mod_start = 0x1C6000;
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pmultiboot_module->mod_end = 0x1C6000 + (INITRD_MB * 1024 * 1024);
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next_avail_mem += sizeof(multiboot_module_t);
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pmultiboot_module->cmdline = next_avail_mem;
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strcpy((char *) next_avail_mem, "fiwix.ext2");
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next_avail_mem += (strlen("fiwix.ext2") + 1);
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/* Set memory map info */
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pmultiboot_info->mmap_addr = next_avail_mem;
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pmultiboot_info->mmap_length = 7 * sizeof(multiboot_memory_map_t);
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multiboot_memory_map_t *pmultiboot_memory_map = (multiboot_memory_map_t *) next_avail_mem;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x00000000;
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pmultiboot_memory_map->len = 0x00080000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_AVAILABLE;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x00080000;
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pmultiboot_memory_map->len = 0x00020000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x000F0000;
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pmultiboot_memory_map->len = 0x00010000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0x00100000;
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pmultiboot_memory_map->len = 0xBC000000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_AVAILABLE;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0XBC000000;
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pmultiboot_memory_map->len = 0x04000000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0XFEFFC000;
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pmultiboot_memory_map->len = 0x00004000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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pmultiboot_memory_map->size = sizeof(multiboot_memory_map_t) - sizeof(multiboot_uint32_t);
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pmultiboot_memory_map->addr = 0XFFFC0000;
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pmultiboot_memory_map->len = 0x00040000;
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pmultiboot_memory_map->type = MULTIBOOT_MEMORY_RESERVED;
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pmultiboot_memory_map++;
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next_avail_mem += pmultiboot_info->mmap_length;
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/* Set boot loader name */
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pmultiboot_info->boot_loader_name = next_avail_mem;
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strcpy((char *) next_avail_mem, boot_loader_name);
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/* next_avail_mem += (strlen(boot_loader_name) + 1); */
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/* Jump to kernel entry point */
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unsigned int magic = MULTIBOOT_BOOTLOADER_MAGIC;
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unsigned int dummy = 0;
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unsigned int multiboot_info_num = (unsigned int) pmultiboot_info;
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int filenum;
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unsigned int filename_addr;
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for (filenum = 4, filename_addr = 0x201000; filenum <= 14335; filenum++, filename_addr += 1024) {
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if (!strcmp((char *) filename_addr, "/boot/fiwix.ext2")) {
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printf("Found image at filenum %d\n", filenum);
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break;
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}
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}
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unsigned int initrd_src = *((unsigned int *) (0x01000000 + (16 * filenum) + 4));
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unsigned int initrd_len = *((unsigned int *) (0x01000000 + (16 * filenum) + 8));
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printf("initrd_src: 0x%08x\n", initrd_src);
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printf("initrd_len: 0x%08x\n", initrd_len);
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printf("Preparing trampoline...\n");
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/* The ramdrive needs to be written to a location that would overwrite this program.
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* Therfore, the code that copies the ram drive and jumps to the kernel needs to be
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* run from a safe location. So, we put that code into an array variable and
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* copy the code (called a "trampoline") to a safe location and then jump to it.
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* The 0x00000000 values below are place holders which are set below
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*/
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char trampoline[] = {
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0xBE, 0x00, 0x00, 0x00, 0x00, /* mov esi, 0x00000000 */
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0xBF, 0x00, 0x00, 0x00, 0x00, /* mov edi, 0x00000000 */
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0xB9, 0x00, 0x00, 0x00, 0x00, /* mov ecx, 0x00000000 */
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0xFC, /* cld */
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0xF3, 0xA4, /* rep movsb */
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0xB8, 0x00, 0x00, 0x00, 0x00, /* mov eax, 0x00000000 */
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0xBB, 0x00, 0x00, 0x00, 0x00, /* mov ebx, 0x00000000 */
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0xFB, /* sti */
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0xEA, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00 /* jmp far 0x0008:0x00000000 */
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};
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/* Set place holder values */
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*((unsigned int *) &trampoline[1]) = initrd_src;
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*((unsigned int *) &trampoline[6]) = 0x001C6000;
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*((unsigned int *) &trampoline[11]) = INITRD_MB * 1024 * 1024;
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*((unsigned int *) &trampoline[19]) = magic;
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*((unsigned int *) &trampoline[24]) = multiboot_info_num;
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*((unsigned int *) &trampoline[30]) = e_entry;
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memcpy((void *)0x4000, trampoline, sizeof(trampoline));
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printf("kexec-fiwix: jumping to trampoline...\n");
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__asm__ __volatile__ (
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"ljmp $0x8, $0x00004000\n\t"
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);
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}
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