hw/arm/boot.c

   1 /*
   2  * ARM kernel loader.
   3  *
   4  * Copyright (c) 2006-2007 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licensed under the GPL.
   8  */
   9
  10 #include "config.h"
  11 #include "hw/hw.h"
  12 #include "hw/arm/arm.h"
  13 #include "sysemu/sysemu.h"
  14 #include "hw/boards.h"
  15 #include "hw/loader.h"
  16 #include "elf.h"
  17 #include "sysemu/device_tree.h"
  18 #include "qemu/config-file.h"
  19 #include "exec/address-spaces.h"
  20
  21 /* Kernel boot protocol is specified in the kernel docs
  22  * Documentation/arm/Booting and Documentation/arm64/booting.txt
  23  * They have different preferred image load offsets from system RAM base.
  24  */
  25 #define KERNEL_ARGS_ADDR 0x100
  26 #define KERNEL_LOAD_ADDR 0x00010000
  27 #define KERNEL64_LOAD_ADDR 0x00080000
  28
  29 typedef enum {
  30     FIXUP_NONE = 0,   /* do nothing */
  31     FIXUP_TERMINATOR, /* end of insns */
  32     FIXUP_BOARDID,    /* overwrite with board ID number */
  33     FIXUP_ARGPTR,     /* overwrite with pointer to kernel args */
  34     FIXUP_ENTRYPOINT, /* overwrite with kernel entry point */
  35     FIXUP_GIC_CPU_IF, /* overwrite with GIC CPU interface address */
  36     FIXUP_BOOTREG,    /* overwrite with boot register address */
  37     FIXUP_DSB,        /* overwrite with correct DSB insn for cpu */
  38     FIXUP_MAX,
  39 } FixupType;
  40
  41 typedef struct ARMInsnFixup {
  42     uint32_t insn;
  43     FixupType fixup;
  44 } ARMInsnFixup;
  45
  46 static const ARMInsnFixup bootloader_aarch64[] = {
  47     { 0x580000c0 }, /* ldr x0, arg ; Load the lower 32-bits of DTB */
  48     { 0xaa1f03e1 }, /* mov x1, xzr */
  49     { 0xaa1f03e2 }, /* mov x2, xzr */
  50     { 0xaa1f03e3 }, /* mov x3, xzr */
  51     { 0x58000084 }, /* ldr x4, entry ; Load the lower 32-bits of kernel entry */
  52     { 0xd61f0080 }, /* br x4      ; Jump to the kernel entry point */
  53     { 0, FIXUP_ARGPTR }, /* arg: .word @DTB Lower 32-bits */
  54     { 0 }, /* .word @DTB Higher 32-bits */
  55     { 0, FIXUP_ENTRYPOINT }, /* entry: .word @Kernel Entry Lower 32-bits */
  56     { 0 }, /* .word @Kernel Entry Higher 32-bits */
  57     { 0, FIXUP_TERMINATOR }
  58 };
  59
  60 /* The worlds second smallest bootloader.  Set r0-r2, then jump to kernel.  */
  61 static const ARMInsnFixup bootloader[] = {
  62     { 0xe3a00000 }, /* mov     r0, #0 */
  63     { 0xe59f1004 }, /* ldr     r1, [pc, #4] */
  64     { 0xe59f2004 }, /* ldr     r2, [pc, #4] */
  65     { 0xe59ff004 }, /* ldr     pc, [pc, #4] */
  66     { 0, FIXUP_BOARDID },
  67     { 0, FIXUP_ARGPTR },
  68     { 0, FIXUP_ENTRYPOINT },
  69     { 0, FIXUP_TERMINATOR }
  70 };
  71
  72 /* Handling for secondary CPU boot in a multicore system.
  73  * Unlike the uniprocessor/primary CPU boot, this is platform
  74  * dependent. The default code here is based on the secondary
  75  * CPU boot protocol used on realview/vexpress boards, with
  76  * some parameterisation to increase its flexibility.
  77  * QEMU platform models for which this code is not appropriate
  78  * should override write_secondary_boot and secondary_cpu_reset_hook
  79  * instead.
  80  *
  81  * This code enables the interrupt controllers for the secondary
  82  * CPUs and then puts all the secondary CPUs into a loop waiting
  83  * for an interprocessor interrupt and polling a configurable
  84  * location for the kernel secondary CPU entry point.
  85  */
  86 #define DSB_INSN 0xf57ff04f
  87 #define CP15_DSB_INSN 0xee070f9a /* mcr cp15, 0, r0, c7, c10, 4 */
  88
  89 static const ARMInsnFixup smpboot[] = {
  90     { 0xe59f2028 }, /* ldr r2, gic_cpu_if */
  91     { 0xe59f0028 }, /* ldr r0, bootreg_addr */
  92     { 0xe3a01001 }, /* mov r1, #1 */
  93     { 0xe5821000 }, /* str r1, [r2] - set GICC_CTLR.Enable */
  94     { 0xe3a010ff }, /* mov r1, #0xff */
  95     { 0xe5821004 }, /* str r1, [r2, 4] - set GIC_PMR.Priority to 0xff */
  96     { 0, FIXUP_DSB },   /* dsb */
  97     { 0xe320f003 }, /* wfi */
  98     { 0xe5901000 }, /* ldr     r1, [r0] */
  99     { 0xe1110001 }, /* tst     r1, r1 */
 100     { 0x0afffffb }, /* beq     <wfi> */
 101     { 0xe12fff11 }, /* bx      r1 */
 102     { 0, FIXUP_GIC_CPU_IF }, /* gic_cpu_if: .word 0x.... */
 103     { 0, FIXUP_BOOTREG }, /* bootreg_addr: .word 0x.... */
 104     { 0, FIXUP_TERMINATOR }
 105 };
 106
 107 static void write_bootloader(const char *name, hwaddr addr,
 108                              const ARMInsnFixup *insns, uint32_t *fixupcontext)
 109 {
 110     /* Fix up the specified bootloader fragment and write it into
 111      * guest memory using rom_add_blob_fixed(). fixupcontext is
 112      * an array giving the values to write in for the fixup types
 113      * which write a value into the code array.
 114      */
 115     int i, len;
 116     uint32_t *code;
 117
 118     len = 0;
 119     while (insns[len].fixup != FIXUP_TERMINATOR) {
 120         len++;
 121     }
 122
 123     code = g_new0(uint32_t, len);
 124
 125     for (i = 0; i < len; i++) {
 126         uint32_t insn = insns[i].insn;
 127         FixupType fixup = insns[i].fixup;
 128
 129         switch (fixup) {
 130         case FIXUP_NONE:
 131             break;
 132         case FIXUP_BOARDID:
 133         case FIXUP_ARGPTR:
 134         case FIXUP_ENTRYPOINT:
 135         case FIXUP_GIC_CPU_IF:
 136         case FIXUP_BOOTREG:
 137         case FIXUP_DSB:
 138             insn = fixupcontext[fixup];
 139             break;
 140         default:
 141             abort();
 142         }
 143         code[i] = tswap32(insn);
 144     }
 145
 146     rom_add_blob_fixed(name, code, len * sizeof(uint32_t), addr);
 147
 148     g_free(code);
 149 }
 150
 151 static void default_write_secondary(ARMCPU *cpu,
 152                                     const struct arm_boot_info *info)
 153 {
 154     uint32_t fixupcontext[FIXUP_MAX];
 155
 156     fixupcontext[FIXUP_GIC_CPU_IF] = info->gic_cpu_if_addr;
 157     fixupcontext[FIXUP_BOOTREG] = info->smp_bootreg_addr;
 158     if (arm_feature(&cpu->env, ARM_FEATURE_V7)) {
 159         fixupcontext[FIXUP_DSB] = DSB_INSN;
 160     } else {
 161         fixupcontext[FIXUP_DSB] = CP15_DSB_INSN;
 162     }
 163
 164     write_bootloader("smpboot", info->smp_loader_start,
 165                      smpboot, fixupcontext);
 166 }
 167
 168 static void default_reset_secondary(ARMCPU *cpu,
 169                                     const struct arm_boot_info *info)
 170 {
 171     CPUARMState *env = &cpu->env;
 172
 173     stl_phys_notdirty(&address_space_memory, info->smp_bootreg_addr, 0);
 174     env->regs[15] = info->smp_loader_start;
 175 }
 176
 177 static inline bool have_dtb(const struct arm_boot_info *info)
 178 {
 179     return info->dtb_filename || info->get_dtb;
 180 }
 181
 182 #define WRITE_WORD(p, value) do { \
 183     stl_phys_notdirty(&address_space_memory, p, value);  \
 184     p += 4;                       \
 185 } while (0)
 186
 187 static void set_kernel_args(const struct arm_boot_info *info)
 188 {
 189     int initrd_size = info->initrd_size;
 190     hwaddr base = info->loader_start;
 191     hwaddr p;
 192
 193     p = base + KERNEL_ARGS_ADDR;
 194     /* ATAG_CORE */
 195     WRITE_WORD(p, 5);
 196     WRITE_WORD(p, 0x54410001);
 197     WRITE_WORD(p, 1);
 198     WRITE_WORD(p, 0x1000);
 199     WRITE_WORD(p, 0);
 200     /* ATAG_MEM */
 201     /* TODO: handle multiple chips on one ATAG list */
 202     WRITE_WORD(p, 4);
 203     WRITE_WORD(p, 0x54410002);
 204     WRITE_WORD(p, info->ram_size);
 205     WRITE_WORD(p, info->loader_start);
 206     if (initrd_size) {
 207         /* ATAG_INITRD2 */
 208         WRITE_WORD(p, 4);
 209         WRITE_WORD(p, 0x54420005);
 210         WRITE_WORD(p, info->initrd_start);
 211         WRITE_WORD(p, initrd_size);
 212     }
 213     if (info->kernel_cmdline && *info->kernel_cmdline) {
 214         /* ATAG_CMDLINE */
 215         int cmdline_size;
 216
 217         cmdline_size = strlen(info->kernel_cmdline);
 218         cpu_physical_memory_write(p + 8, info->kernel_cmdline,
 219                                   cmdline_size + 1);
 220         cmdline_size = (cmdline_size >> 2) + 1;
 221         WRITE_WORD(p, cmdline_size + 2);
 222         WRITE_WORD(p, 0x54410009);
 223         p += cmdline_size * 4;
 224     }
 225     if (info->atag_board) {
 226         /* ATAG_BOARD */
 227         int atag_board_len;
 228         uint8_t atag_board_buf[0x1000];
 229
 230         atag_board_len = (info->atag_board(info, atag_board_buf) + 3) & ~3;
 231         WRITE_WORD(p, (atag_board_len + 8) >> 2);
 232         WRITE_WORD(p, 0x414f4d50);
 233         cpu_physical_memory_write(p, atag_board_buf, atag_board_len);
 234         p += atag_board_len;
 235     }
 236     /* ATAG_END */
 237     WRITE_WORD(p, 0);
 238     WRITE_WORD(p, 0);
 239 }
 240
 241 static void set_kernel_args_old(const struct arm_boot_info *info)
 242 {
 243     hwaddr p;
 244     const char *s;
 245     int initrd_size = info->initrd_size;
 246     hwaddr base = info->loader_start;
 247
 248     /* see linux/include/asm-arm/setup.h */
 249     p = base + KERNEL_ARGS_ADDR;
 250     /* page_size */
 251     WRITE_WORD(p, 4096);
 252     /* nr_pages */
 253     WRITE_WORD(p, info->ram_size / 4096);
 254     /* ramdisk_size */
 255     WRITE_WORD(p, 0);
 256 #define FLAG_READONLY   1
 257 #define FLAG_RDLOAD     4
 258 #define FLAG_RDPROMPT   8
 259     /* flags */
 260     WRITE_WORD(p, FLAG_READONLY | FLAG_RDLOAD | FLAG_RDPROMPT);
 261     /* rootdev */
 262     WRITE_WORD(p, (31 << 8) | 0);       /* /dev/mtdblock0 */
 263     /* video_num_cols */
 264     WRITE_WORD(p, 0);
 265     /* video_num_rows */
 266     WRITE_WORD(p, 0);
 267     /* video_x */
 268     WRITE_WORD(p, 0);
 269     /* video_y */
 270     WRITE_WORD(p, 0);
 271     /* memc_control_reg */
 272     WRITE_WORD(p, 0);
 273     /* unsigned char sounddefault */
 274     /* unsigned char adfsdrives */
 275     /* unsigned char bytes_per_char_h */
 276     /* unsigned char bytes_per_char_v */
 277     WRITE_WORD(p, 0);
 278     /* pages_in_bank[4] */
 279     WRITE_WORD(p, 0);
 280     WRITE_WORD(p, 0);
 281     WRITE_WORD(p, 0);
 282     WRITE_WORD(p, 0);
 283     /* pages_in_vram */
 284     WRITE_WORD(p, 0);
 285     /* initrd_start */
 286     if (initrd_size) {
 287         WRITE_WORD(p, info->initrd_start);
 288     } else {
 289         WRITE_WORD(p, 0);
 290     }
 291     /* initrd_size */
 292     WRITE_WORD(p, initrd_size);
 293     /* rd_start */
 294     WRITE_WORD(p, 0);
 295     /* system_rev */
 296     WRITE_WORD(p, 0);
 297     /* system_serial_low */
 298     WRITE_WORD(p, 0);
 299     /* system_serial_high */
 300     WRITE_WORD(p, 0);
 301     /* mem_fclk_21285 */
 302     WRITE_WORD(p, 0);
 303     /* zero unused fields */
 304     while (p < base + KERNEL_ARGS_ADDR + 256 + 1024) {
 305         WRITE_WORD(p, 0);
 306     }
 307     s = info->kernel_cmdline;
 308     if (s) {
 309         cpu_physical_memory_write(p, s, strlen(s) + 1);
 310     } else {
 311         WRITE_WORD(p, 0);
 312     }
 313 }
 314
 315 /**
 316  * load_dtb() - load a device tree binary image into memory
 317  * @addr:       the address to load the image at
 318  * @binfo:      struct describing the boot environment
 319  * @addr_limit: upper limit of the available memory area at @addr
 320  *
 321  * Load a device tree supplied by the machine or by the user  with the
 322  * '-dtb' command line option, and put it at offset @addr in target
 323  * memory.
 324  *
 325  * If @addr_limit contains a meaningful value (i.e., it is strictly greater
 326  * than @addr), the device tree is only loaded if its size does not exceed
 327  * the limit.
 328  *
 329  * Returns: the size of the device tree image on success,
 330  *          0 if the image size exceeds the limit,
 331  *          -1 on errors.
 332  */
 333 static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
 334                     hwaddr addr_limit)
 335 {
 336     void *fdt = NULL;
 337     int size, rc;
 338     uint32_t acells, scells;
 339
 340     if (binfo->dtb_filename) {
 341         char *filename;
 342         filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
 343         if (!filename) {
 344             fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
 345             goto fail;
 346         }
 347
 348         fdt = load_device_tree(filename, &size);
 349         if (!fdt) {
 350             fprintf(stderr, "Couldn't open dtb file %s\n", filename);
 351             g_free(filename);
 352             goto fail;
 353         }
 354         g_free(filename);
 355     } else if (binfo->get_dtb) {
 356         fdt = binfo->get_dtb(binfo, &size);
 357         if (!fdt) {
 358             fprintf(stderr, "Board was unable to create a dtb blob\n");
 359             goto fail;
 360         }
 361     }
 362
 363     if (addr_limit > addr && size > (addr_limit - addr)) {
 364         /* Installing the device tree blob at addr would exceed addr_limit.
 365          * Whether this constitutes failure is up to the caller to decide,
 366          * so just return 0 as size, i.e., no error.
 367          */
 368         g_free(fdt);
 369         return 0;
 370     }
 371
 372     acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells");
 373     scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells");
 374     if (acells == 0 || scells == 0) {
 375         fprintf(stderr, "dtb file invalid (#address-cells or #size-cells 0)\n");
 376         goto fail;
 377     }
 378
 379     if (scells < 2 && binfo->ram_size >= (1ULL << 32)) {
 380         /* This is user error so deserves a friendlier error message
 381          * than the failure of setprop_sized_cells would provide
 382          */
 383         fprintf(stderr, "qemu: dtb file not compatible with "
 384                 "RAM size > 4GB\n");
 385         goto fail;
 386     }
 387
 388     rc = qemu_fdt_setprop_sized_cells(fdt, "/memory", "reg",
 389                                       acells, binfo->loader_start,
 390                                       scells, binfo->ram_size);
 391     if (rc < 0) {
 392         fprintf(stderr, "couldn't set /memory/reg\n");
 393         goto fail;
 394     }
 395
 396     if (binfo->kernel_cmdline && *binfo->kernel_cmdline) {
 397         rc = qemu_fdt_setprop_string(fdt, "/chosen", "bootargs",
 398                                      binfo->kernel_cmdline);
 399         if (rc < 0) {
 400             fprintf(stderr, "couldn't set /chosen/bootargs\n");
 401             goto fail;
 402         }
 403     }
 404
 405     if (binfo->initrd_size) {
 406         rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-start",
 407                                    binfo->initrd_start);
 408         if (rc < 0) {
 409             fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
 410             goto fail;
 411         }
 412
 413         rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-end",
 414                                    binfo->initrd_start + binfo->initrd_size);
 415         if (rc < 0) {
 416             fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
 417             goto fail;
 418         }
 419     }
 420
 421     if (binfo->modify_dtb) {
 422         binfo->modify_dtb(binfo, fdt);
 423     }
 424
 425     qemu_fdt_dumpdtb(fdt, size);
 426
 427     /* Put the DTB into the memory map as a ROM image: this will ensure
 428      * the DTB is copied again upon reset, even if addr points into RAM.
 429      */
 430     rom_add_blob_fixed("dtb", fdt, size, addr);
 431
 432     g_free(fdt);
 433
 434     return size;
 435
 436 fail:
 437     g_free(fdt);
 438     return -1;
 439 }
 440
 441 static void do_cpu_reset(void *opaque)
 442 {
 443     ARMCPU *cpu = opaque;
 444     CPUARMState *env = &cpu->env;
 445     const struct arm_boot_info *info = env->boot_info;
 446
 447     cpu_reset(CPU(cpu));
 448     if (info) {
 449         if (!info->is_linux) {
 450             /* Jump to the entry point.  */
 451             if (env->aarch64) {
 452                 env->pc = info->entry;
 453             } else {
 454                 env->regs[15] = info->entry & 0xfffffffe;
 455                 env->thumb = info->entry & 1;
 456             }
 457         } else {
 458             if (CPU(cpu) == first_cpu) {
 459                 if (env->aarch64) {
 460                     env->pc = info->loader_start;
 461                 } else {
 462                     env->regs[15] = info->loader_start;
 463                 }
 464
 465                 if (!have_dtb(info)) {
 466                     if (old_param) {
 467                         set_kernel_args_old(info);
 468                     } else {
 469                         set_kernel_args(info);
 470                     }
 471                 }
 472             } else {
 473                 info->secondary_cpu_reset_hook(cpu, info);
 474             }
 475         }
 476     }
 477 }
 478
 479 void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
 480 {
 481     CPUState *cs = CPU(cpu);
 482     int kernel_size;
 483     int initrd_size;
 484     int is_linux = 0;
 485     uint64_t elf_entry, elf_low_addr, elf_high_addr;
 486     int elf_machine;
 487     hwaddr entry, kernel_load_offset;
 488     int big_endian;
 489     static const ARMInsnFixup *primary_loader;
 490
 491     /* Load the kernel.  */
 492     if (!info->kernel_filename) {
 493
 494         if (have_dtb(info)) {
 495             /* If we have a device tree blob, but no kernel to supply it to,
 496              * copy it to the base of RAM for a bootloader to pick up.
 497              */
 498             if (load_dtb(info->loader_start, info, 0) < 0) {
 499                 exit(1);
 500             }
 501         }
 502
 503         /* If no kernel specified, do nothing; we will start from address 0
 504          * (typically a boot ROM image) in the same way as hardware.
 505          */
 506         return;
 507     }
 508
 509     if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
 510         primary_loader = bootloader_aarch64;
 511         kernel_load_offset = KERNEL64_LOAD_ADDR;
 512         elf_machine = EM_AARCH64;
 513     } else {
 514         primary_loader = bootloader;
 515         kernel_load_offset = KERNEL_LOAD_ADDR;
 516         elf_machine = EM_ARM;
 517     }
 518
 519     info->dtb_filename = qemu_opt_get(qemu_get_machine_opts(), "dtb");
 520
 521     if (!info->secondary_cpu_reset_hook) {
 522         info->secondary_cpu_reset_hook = default_reset_secondary;
 523     }
 524     if (!info->write_secondary_boot) {
 525         info->write_secondary_boot = default_write_secondary;
 526     }
 527
 528     if (info->nb_cpus == 0)
 529         info->nb_cpus = 1;
 530
 531 #ifdef TARGET_WORDS_BIGENDIAN
 532     big_endian = 1;
 533 #else
 534     big_endian = 0;
 535 #endif
 536
 537     /* We want to put the initrd far enough into RAM that when the
 538      * kernel is uncompressed it will not clobber the initrd. However
 539      * on boards without much RAM we must ensure that we still leave
 540      * enough room for a decent sized initrd, and on boards with large
 541      * amounts of RAM we must avoid the initrd being so far up in RAM
 542      * that it is outside lowmem and inaccessible to the kernel.
 543      * So for boards with less  than 256MB of RAM we put the initrd
 544      * halfway into RAM, and for boards with 256MB of RAM or more we put
 545      * the initrd at 128MB.
 546      */
 547     info->initrd_start = info->loader_start +
 548         MIN(info->ram_size / 2, 128 * 1024 * 1024);
 549
 550     /* Assume that raw images are linux kernels, and ELF images are not.  */
 551     kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry,
 552                            &elf_low_addr, &elf_high_addr, big_endian,
 553                            elf_machine, 1);
 554     if (kernel_size > 0 && have_dtb(info)) {
 555         /* If there is still some room left at the base of RAM, try and put
 556          * the DTB there like we do for images loaded with -bios or -pflash.
 557          */
 558         if (elf_low_addr > info->loader_start
 559             || elf_high_addr < info->loader_start) {
 560             /* Pass elf_low_addr as address limit to load_dtb if it may be
 561              * pointing into RAM, otherwise pass '0' (no limit)
 562              */
 563             if (elf_low_addr < info->loader_start) {
 564                 elf_low_addr = 0;
 565             }
 566             if (load_dtb(info->loader_start, info, elf_low_addr) < 0) {
 567                 exit(1);
 568             }
 569         }
 570     }
 571     entry = elf_entry;
 572     if (kernel_size < 0) {
 573         kernel_size = load_uimage(info->kernel_filename, &entry, NULL,
 574                                   &is_linux);
 575     }
 576     /* On aarch64, it's the bootloader's job to uncompress the kernel. */
 577     if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) {
 578         entry = info->loader_start + kernel_load_offset;
 579         kernel_size = load_image_gzipped(info->kernel_filename, entry,
 580                                          info->ram_size - kernel_load_offset);
 581         is_linux = 1;
 582     }
 583     if (kernel_size < 0) {
 584         entry = info->loader_start + kernel_load_offset;
 585         kernel_size = load_image_targphys(info->kernel_filename, entry,
 586                                           info->ram_size - kernel_load_offset);
 587         is_linux = 1;
 588     }
 589     if (kernel_size < 0) {
 590         fprintf(stderr, "qemu: could not load kernel '%s'\n",
 591                 info->kernel_filename);
 592         exit(1);
 593     }
 594     info->entry = entry;
 595     if (is_linux) {
 596         uint32_t fixupcontext[FIXUP_MAX];
 597
 598         if (info->initrd_filename) {
 599             initrd_size = load_ramdisk(info->initrd_filename,
 600                                        info->initrd_start,
 601                                        info->ram_size -
 602                                        info->initrd_start);
 603             if (initrd_size < 0) {
 604                 initrd_size = load_image_targphys(info->initrd_filename,
 605                                                   info->initrd_start,
 606                                                   info->ram_size -
 607                                                   info->initrd_start);
 608             }
 609             if (initrd_size < 0) {
 610                 fprintf(stderr, "qemu: could not load initrd '%s'\n",
 611                         info->initrd_filename);
 612                 exit(1);
 613             }
 614         } else {
 615             initrd_size = 0;
 616         }
 617         info->initrd_size = initrd_size;
 618
 619         fixupcontext[FIXUP_BOARDID] = info->board_id;
 620
 621         /* for device tree boot, we pass the DTB directly in r2. Otherwise
 622          * we point to the kernel args.
 623          */
 624         if (have_dtb(info)) {
 625             /* Place the DTB after the initrd in memory. Note that some
 626              * kernels will trash anything in the 4K page the initrd
 627              * ends in, so make sure the DTB isn't caught up in that.
 628              */
 629             hwaddr dtb_start = QEMU_ALIGN_UP(info->initrd_start + initrd_size,
 630                                              4096);
 631             if (load_dtb(dtb_start, info, 0) < 0) {
 632                 exit(1);
 633             }
 634             fixupcontext[FIXUP_ARGPTR] = dtb_start;
 635         } else {
 636             fixupcontext[FIXUP_ARGPTR] = info->loader_start + KERNEL_ARGS_ADDR;
 637             if (info->ram_size >= (1ULL << 32)) {
 638                 fprintf(stderr, "qemu: RAM size must be less than 4GB to boot"
 639                         " Linux kernel using ATAGS (try passing a device tree"
 640                         " using -dtb)\n");
 641                 exit(1);
 642             }
 643         }
 644         fixupcontext[FIXUP_ENTRYPOINT] = entry;
 645
 646         write_bootloader("bootloader", info->loader_start,
 647                          primary_loader, fixupcontext);
 648
 649         if (info->nb_cpus > 1) {
 650             info->write_secondary_boot(cpu, info);
 651         }
 652     }
 653     info->is_linux = is_linux;
 654
 655     for (; cs; cs = CPU_NEXT(cs)) {
 656         cpu = ARM_CPU(cs);
 657         cpu->env.boot_info = info;
 658         qemu_register_reset(do_cpu_reset, cpu);
 659     }
 660 }