summaryrefslogtreecommitdiff
path: root/hw/arm/boot.c
blob: c8d1d4e147e254ada6c729fd320cb44bb95b05c5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
/*
 * ARM kernel loader.
 *
 * Copyright (c) 2006-2007 CodeSourcery.
 * Written by Paul Brook
 *
 * This code is licensed under the GPL.
 */

#include "config.h"
#include "hw/hw.h"
#include "hw/arm/arm.h"
#include "sysemu/sysemu.h"
#include "hw/boards.h"
#include "hw/loader.h"
#include "elf.h"
#include "sysemu/device_tree.h"
#include "qemu/config-file.h"
#include "exec/address-spaces.h"

/* Kernel boot protocol is specified in the kernel docs
 * Documentation/arm/Booting and Documentation/arm64/booting.txt
 * They have different preferred image load offsets from system RAM base.
 */
#define KERNEL_ARGS_ADDR 0x100
#define KERNEL_LOAD_ADDR 0x00010000
#define KERNEL64_LOAD_ADDR 0x00080000

typedef enum {
    FIXUP_NONE = 0,   /* do nothing */
    FIXUP_TERMINATOR, /* end of insns */
    FIXUP_BOARDID,    /* overwrite with board ID number */
    FIXUP_ARGPTR,     /* overwrite with pointer to kernel args */
    FIXUP_ENTRYPOINT, /* overwrite with kernel entry point */
    FIXUP_GIC_CPU_IF, /* overwrite with GIC CPU interface address */
    FIXUP_BOOTREG,    /* overwrite with boot register address */
    FIXUP_DSB,        /* overwrite with correct DSB insn for cpu */
    FIXUP_MAX,
} FixupType;

typedef struct ARMInsnFixup {
    uint32_t insn;
    FixupType fixup;
} ARMInsnFixup;

static const ARMInsnFixup bootloader_aarch64[] = {
    { 0x580000c0 }, /* ldr x0, arg ; Load the lower 32-bits of DTB */
    { 0xaa1f03e1 }, /* mov x1, xzr */
    { 0xaa1f03e2 }, /* mov x2, xzr */
    { 0xaa1f03e3 }, /* mov x3, xzr */
    { 0x58000084 }, /* ldr x4, entry ; Load the lower 32-bits of kernel entry */
    { 0xd61f0080 }, /* br x4      ; Jump to the kernel entry point */
    { 0, FIXUP_ARGPTR }, /* arg: .word @DTB Lower 32-bits */
    { 0 }, /* .word @DTB Higher 32-bits */
    { 0, FIXUP_ENTRYPOINT }, /* entry: .word @Kernel Entry Lower 32-bits */
    { 0 }, /* .word @Kernel Entry Higher 32-bits */
    { 0, FIXUP_TERMINATOR }
};

/* The worlds second smallest bootloader.  Set r0-r2, then jump to kernel.  */
static const ARMInsnFixup bootloader[] = {
    { 0xe3a00000 }, /* mov     r0, #0 */
    { 0xe59f1004 }, /* ldr     r1, [pc, #4] */
    { 0xe59f2004 }, /* ldr     r2, [pc, #4] */
    { 0xe59ff004 }, /* ldr     pc, [pc, #4] */
    { 0, FIXUP_BOARDID },
    { 0, FIXUP_ARGPTR },
    { 0, FIXUP_ENTRYPOINT },
    { 0, FIXUP_TERMINATOR }
};

/* Handling for secondary CPU boot in a multicore system.
 * Unlike the uniprocessor/primary CPU boot, this is platform
 * dependent. The default code here is based on the secondary
 * CPU boot protocol used on realview/vexpress boards, with
 * some parameterisation to increase its flexibility.
 * QEMU platform models for which this code is not appropriate
 * should override write_secondary_boot and secondary_cpu_reset_hook
 * instead.
 *
 * This code enables the interrupt controllers for the secondary
 * CPUs and then puts all the secondary CPUs into a loop waiting
 * for an interprocessor interrupt and polling a configurable
 * location for the kernel secondary CPU entry point.
 */
#define DSB_INSN 0xf57ff04f
#define CP15_DSB_INSN 0xee070f9a /* mcr cp15, 0, r0, c7, c10, 4 */

static const ARMInsnFixup smpboot[] = {
    { 0xe59f2028 }, /* ldr r2, gic_cpu_if */
    { 0xe59f0028 }, /* ldr r0, bootreg_addr */
    { 0xe3a01001 }, /* mov r1, #1 */
    { 0xe5821000 }, /* str r1, [r2] - set GICC_CTLR.Enable */
    { 0xe3a010ff }, /* mov r1, #0xff */
    { 0xe5821004 }, /* str r1, [r2, 4] - set GIC_PMR.Priority to 0xff */
    { 0, FIXUP_DSB },   /* dsb */
    { 0xe320f003 }, /* wfi */
    { 0xe5901000 }, /* ldr     r1, [r0] */
    { 0xe1110001 }, /* tst     r1, r1 */
    { 0x0afffffb }, /* beq     <wfi> */
    { 0xe12fff11 }, /* bx      r1 */
    { 0, FIXUP_GIC_CPU_IF }, /* gic_cpu_if: .word 0x.... */
    { 0, FIXUP_BOOTREG }, /* bootreg_addr: .word 0x.... */
    { 0, FIXUP_TERMINATOR }
};

static void write_bootloader(const char *name, hwaddr addr,
                             const ARMInsnFixup *insns, uint32_t *fixupcontext)
{
    /* Fix up the specified bootloader fragment and write it into
     * guest memory using rom_add_blob_fixed(). fixupcontext is
     * an array giving the values to write in for the fixup types
     * which write a value into the code array.
     */
    int i, len;
    uint32_t *code;

    len = 0;
    while (insns[len].fixup != FIXUP_TERMINATOR) {
        len++;
    }

    code = g_new0(uint32_t, len);

    for (i = 0; i < len; i++) {
        uint32_t insn = insns[i].insn;
        FixupType fixup = insns[i].fixup;

        switch (fixup) {
        case FIXUP_NONE:
            break;
        case FIXUP_BOARDID:
        case FIXUP_ARGPTR:
        case FIXUP_ENTRYPOINT:
        case FIXUP_GIC_CPU_IF:
        case FIXUP_BOOTREG:
        case FIXUP_DSB:
            insn = fixupcontext[fixup];
            break;
        default:
            abort();
        }
        code[i] = tswap32(insn);
    }

    rom_add_blob_fixed(name, code, len * sizeof(uint32_t), addr);

    g_free(code);
}

static void default_write_secondary(ARMCPU *cpu,
                                    const struct arm_boot_info *info)
{
    uint32_t fixupcontext[FIXUP_MAX];

    fixupcontext[FIXUP_GIC_CPU_IF] = info->gic_cpu_if_addr;
    fixupcontext[FIXUP_BOOTREG] = info->smp_bootreg_addr;
    if (arm_feature(&cpu->env, ARM_FEATURE_V7)) {
        fixupcontext[FIXUP_DSB] = DSB_INSN;
    } else {
        fixupcontext[FIXUP_DSB] = CP15_DSB_INSN;
    }

    write_bootloader("smpboot", info->smp_loader_start,
                     smpboot, fixupcontext);
}

static void default_reset_secondary(ARMCPU *cpu,
                                    const struct arm_boot_info *info)
{
    CPUARMState *env = &cpu->env;

    stl_phys_notdirty(&address_space_memory, info->smp_bootreg_addr, 0);
    env->regs[15] = info->smp_loader_start;
}

static inline bool have_dtb(const struct arm_boot_info *info)
{
    return info->dtb_filename || info->get_dtb;
}

#define WRITE_WORD(p, value) do { \
    stl_phys_notdirty(&address_space_memory, p, value);  \
    p += 4;                       \
} while (0)

static void set_kernel_args(const struct arm_boot_info *info)
{
    int initrd_size = info->initrd_size;
    hwaddr base = info->loader_start;
    hwaddr p;

    p = base + KERNEL_ARGS_ADDR;
    /* ATAG_CORE */
    WRITE_WORD(p, 5);
    WRITE_WORD(p, 0x54410001);
    WRITE_WORD(p, 1);
    WRITE_WORD(p, 0x1000);
    WRITE_WORD(p, 0);
    /* ATAG_MEM */
    /* TODO: handle multiple chips on one ATAG list */
    WRITE_WORD(p, 4);
    WRITE_WORD(p, 0x54410002);
    WRITE_WORD(p, info->ram_size);
    WRITE_WORD(p, info->loader_start);
    if (initrd_size) {
        /* ATAG_INITRD2 */
        WRITE_WORD(p, 4);
        WRITE_WORD(p, 0x54420005);
        WRITE_WORD(p, info->initrd_start);
        WRITE_WORD(p, initrd_size);
    }
    if (info->kernel_cmdline && *info->kernel_cmdline) {
        /* ATAG_CMDLINE */
        int cmdline_size;

        cmdline_size = strlen(info->kernel_cmdline);
        cpu_physical_memory_write(p + 8, info->kernel_cmdline,
                                  cmdline_size + 1);
        cmdline_size = (cmdline_size >> 2) + 1;
        WRITE_WORD(p, cmdline_size + 2);
        WRITE_WORD(p, 0x54410009);
        p += cmdline_size * 4;
    }
    if (info->atag_board) {
        /* ATAG_BOARD */
        int atag_board_len;
        uint8_t atag_board_buf[0x1000];

        atag_board_len = (info->atag_board(info, atag_board_buf) + 3) & ~3;
        WRITE_WORD(p, (atag_board_len + 8) >> 2);
        WRITE_WORD(p, 0x414f4d50);
        cpu_physical_memory_write(p, atag_board_buf, atag_board_len);
        p += atag_board_len;
    }
    /* ATAG_END */
    WRITE_WORD(p, 0);
    WRITE_WORD(p, 0);
}

static void set_kernel_args_old(const struct arm_boot_info *info)
{
    hwaddr p;
    const char *s;
    int initrd_size = info->initrd_size;
    hwaddr base = info->loader_start;

    /* see linux/include/asm-arm/setup.h */
    p = base + KERNEL_ARGS_ADDR;
    /* page_size */
    WRITE_WORD(p, 4096);
    /* nr_pages */
    WRITE_WORD(p, info->ram_size / 4096);
    /* ramdisk_size */
    WRITE_WORD(p, 0);
#define FLAG_READONLY	1
#define FLAG_RDLOAD	4
#define FLAG_RDPROMPT	8
    /* flags */
    WRITE_WORD(p, FLAG_READONLY | FLAG_RDLOAD | FLAG_RDPROMPT);
    /* rootdev */
    WRITE_WORD(p, (31 << 8) | 0);	/* /dev/mtdblock0 */
    /* video_num_cols */
    WRITE_WORD(p, 0);
    /* video_num_rows */
    WRITE_WORD(p, 0);
    /* video_x */
    WRITE_WORD(p, 0);
    /* video_y */
    WRITE_WORD(p, 0);
    /* memc_control_reg */
    WRITE_WORD(p, 0);
    /* unsigned char sounddefault */
    /* unsigned char adfsdrives */
    /* unsigned char bytes_per_char_h */
    /* unsigned char bytes_per_char_v */
    WRITE_WORD(p, 0);
    /* pages_in_bank[4] */
    WRITE_WORD(p, 0);
    WRITE_WORD(p, 0);
    WRITE_WORD(p, 0);
    WRITE_WORD(p, 0);
    /* pages_in_vram */
    WRITE_WORD(p, 0);
    /* initrd_start */
    if (initrd_size) {
        WRITE_WORD(p, info->initrd_start);
    } else {
        WRITE_WORD(p, 0);
    }
    /* initrd_size */
    WRITE_WORD(p, initrd_size);
    /* rd_start */
    WRITE_WORD(p, 0);
    /* system_rev */
    WRITE_WORD(p, 0);
    /* system_serial_low */
    WRITE_WORD(p, 0);
    /* system_serial_high */
    WRITE_WORD(p, 0);
    /* mem_fclk_21285 */
    WRITE_WORD(p, 0);
    /* zero unused fields */
    while (p < base + KERNEL_ARGS_ADDR + 256 + 1024) {
        WRITE_WORD(p, 0);
    }
    s = info->kernel_cmdline;
    if (s) {
        cpu_physical_memory_write(p, s, strlen(s) + 1);
    } else {
        WRITE_WORD(p, 0);
    }
}

/**
 * load_dtb() - load a device tree binary image into memory
 * @addr:       the address to load the image at
 * @binfo:      struct describing the boot environment
 * @addr_limit: upper limit of the available memory area at @addr
 *
 * Load a device tree supplied by the machine or by the user  with the
 * '-dtb' command line option, and put it at offset @addr in target
 * memory.
 *
 * If @addr_limit contains a meaningful value (i.e., it is strictly greater
 * than @addr), the device tree is only loaded if its size does not exceed
 * the limit.
 *
 * Returns: the size of the device tree image on success,
 *          0 if the image size exceeds the limit,
 *          -1 on errors.
 *
 * Note: Must not be called unless have_dtb(binfo) is true.
 */
static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
                    hwaddr addr_limit)
{
    void *fdt = NULL;
    int size, rc;
    uint32_t acells, scells;

    if (binfo->dtb_filename) {
        char *filename;
        filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
        if (!filename) {
            fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
            goto fail;
        }

        fdt = load_device_tree(filename, &size);
        if (!fdt) {
            fprintf(stderr, "Couldn't open dtb file %s\n", filename);
            g_free(filename);
            goto fail;
        }
        g_free(filename);
    } else {
        fdt = binfo->get_dtb(binfo, &size);
        if (!fdt) {
            fprintf(stderr, "Board was unable to create a dtb blob\n");
            goto fail;
        }
    }

    if (addr_limit > addr && size > (addr_limit - addr)) {
        /* Installing the device tree blob at addr would exceed addr_limit.
         * Whether this constitutes failure is up to the caller to decide,
         * so just return 0 as size, i.e., no error.
         */
        g_free(fdt);
        return 0;
    }

    acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells");
    scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells");
    if (acells == 0 || scells == 0) {
        fprintf(stderr, "dtb file invalid (#address-cells or #size-cells 0)\n");
        goto fail;
    }

    if (scells < 2 && binfo->ram_size >= (1ULL << 32)) {
        /* This is user error so deserves a friendlier error message
         * than the failure of setprop_sized_cells would provide
         */
        fprintf(stderr, "qemu: dtb file not compatible with "
                "RAM size > 4GB\n");
        goto fail;
    }

    rc = qemu_fdt_setprop_sized_cells(fdt, "/memory", "reg",
                                      acells, binfo->loader_start,
                                      scells, binfo->ram_size);
    if (rc < 0) {
        fprintf(stderr, "couldn't set /memory/reg\n");
        goto fail;
    }

    if (binfo->kernel_cmdline && *binfo->kernel_cmdline) {
        rc = qemu_fdt_setprop_string(fdt, "/chosen", "bootargs",
                                     binfo->kernel_cmdline);
        if (rc < 0) {
            fprintf(stderr, "couldn't set /chosen/bootargs\n");
            goto fail;
        }
    }

    if (binfo->initrd_size) {
        rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-start",
                                   binfo->initrd_start);
        if (rc < 0) {
            fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
            goto fail;
        }

        rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-end",
                                   binfo->initrd_start + binfo->initrd_size);
        if (rc < 0) {
            fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
            goto fail;
        }
    }

    if (binfo->modify_dtb) {
        binfo->modify_dtb(binfo, fdt);
    }

    qemu_fdt_dumpdtb(fdt, size);

    /* Put the DTB into the memory map as a ROM image: this will ensure
     * the DTB is copied again upon reset, even if addr points into RAM.
     */
    rom_add_blob_fixed("dtb", fdt, size, addr);

    g_free(fdt);

    return size;

fail:
    g_free(fdt);
    return -1;
}

static void do_cpu_reset(void *opaque)
{
    ARMCPU *cpu = opaque;
    CPUARMState *env = &cpu->env;
    const struct arm_boot_info *info = env->boot_info;

    cpu_reset(CPU(cpu));
    if (info) {
        if (!info->is_linux) {
            /* Jump to the entry point.  */
            if (env->aarch64) {
                env->pc = info->entry;
            } else {
                env->regs[15] = info->entry & 0xfffffffe;
                env->thumb = info->entry & 1;
            }
        } else {
            /* If we are booting Linux then we need to check whether we are
             * booting into secure or non-secure state and adjust the state
             * accordingly.  Out of reset, ARM is defined to be in secure state
             * (SCR.NS = 0), we change that here if non-secure boot has been
             * requested.
             */
            if (arm_feature(env, ARM_FEATURE_EL3) && !info->secure_boot) {
                env->cp15.scr_el3 |= SCR_NS;
            }

            if (CPU(cpu) == first_cpu) {
                if (env->aarch64) {
                    env->pc = info->loader_start;
                } else {
                    env->regs[15] = info->loader_start;
                }

                if (!have_dtb(info)) {
                    if (old_param) {
                        set_kernel_args_old(info);
                    } else {
                        set_kernel_args(info);
                    }
                }
            } else {
                info->secondary_cpu_reset_hook(cpu, info);
            }
        }
    }
}

void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
{
    CPUState *cs;
    int kernel_size;
    int initrd_size;
    int is_linux = 0;
    uint64_t elf_entry, elf_low_addr, elf_high_addr;
    int elf_machine;
    hwaddr entry, kernel_load_offset;
    int big_endian;
    static const ARMInsnFixup *primary_loader;

    /* CPU objects (unlike devices) are not automatically reset on system
     * reset, so we must always register a handler to do so. If we're
     * actually loading a kernel, the handler is also responsible for
     * arranging that we start it correctly.
     */
    for (cs = CPU(cpu); cs; cs = CPU_NEXT(cs)) {
        qemu_register_reset(do_cpu_reset, ARM_CPU(cs));
    }

    /* Load the kernel.  */
    if (!info->kernel_filename) {

        if (have_dtb(info)) {
            /* If we have a device tree blob, but no kernel to supply it to,
             * copy it to the base of RAM for a bootloader to pick up.
             */
            if (load_dtb(info->loader_start, info, 0) < 0) {
                exit(1);
            }
        }

        /* If no kernel specified, do nothing; we will start from address 0
         * (typically a boot ROM image) in the same way as hardware.
         */
        return;
    }

    if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
        primary_loader = bootloader_aarch64;
        kernel_load_offset = KERNEL64_LOAD_ADDR;
        elf_machine = EM_AARCH64;
    } else {
        primary_loader = bootloader;
        kernel_load_offset = KERNEL_LOAD_ADDR;
        elf_machine = EM_ARM;
    }

    info->dtb_filename = qemu_opt_get(qemu_get_machine_opts(), "dtb");

    if (!info->secondary_cpu_reset_hook) {
        info->secondary_cpu_reset_hook = default_reset_secondary;
    }
    if (!info->write_secondary_boot) {
        info->write_secondary_boot = default_write_secondary;
    }

    if (info->nb_cpus == 0)
        info->nb_cpus = 1;

#ifdef TARGET_WORDS_BIGENDIAN
    big_endian = 1;
#else
    big_endian = 0;
#endif

    /* We want to put the initrd far enough into RAM that when the
     * kernel is uncompressed it will not clobber the initrd. However
     * on boards without much RAM we must ensure that we still leave
     * enough room for a decent sized initrd, and on boards with large
     * amounts of RAM we must avoid the initrd being so far up in RAM
     * that it is outside lowmem and inaccessible to the kernel.
     * So for boards with less  than 256MB of RAM we put the initrd
     * halfway into RAM, and for boards with 256MB of RAM or more we put
     * the initrd at 128MB.
     */
    info->initrd_start = info->loader_start +
        MIN(info->ram_size / 2, 128 * 1024 * 1024);

    /* Assume that raw images are linux kernels, and ELF images are not.  */
    kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry,
                           &elf_low_addr, &elf_high_addr, big_endian,
                           elf_machine, 1);
    if (kernel_size > 0 && have_dtb(info)) {
        /* If there is still some room left at the base of RAM, try and put
         * the DTB there like we do for images loaded with -bios or -pflash.
         */
        if (elf_low_addr > info->loader_start
            || elf_high_addr < info->loader_start) {
            /* Pass elf_low_addr as address limit to load_dtb if it may be
             * pointing into RAM, otherwise pass '0' (no limit)
             */
            if (elf_low_addr < info->loader_start) {
                elf_low_addr = 0;
            }
            if (load_dtb(info->loader_start, info, elf_low_addr) < 0) {
                exit(1);
            }
        }
    }
    entry = elf_entry;
    if (kernel_size < 0) {
        kernel_size = load_uimage(info->kernel_filename, &entry, NULL,
                                  &is_linux, NULL, NULL);
    }
    /* On aarch64, it's the bootloader's job to uncompress the kernel. */
    if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) {
        entry = info->loader_start + kernel_load_offset;
        kernel_size = load_image_gzipped(info->kernel_filename, entry,
                                         info->ram_size - kernel_load_offset);
        is_linux = 1;
    }
    if (kernel_size < 0) {
        entry = info->loader_start + kernel_load_offset;
        kernel_size = load_image_targphys(info->kernel_filename, entry,
                                          info->ram_size - kernel_load_offset);
        is_linux = 1;
    }
    if (kernel_size < 0) {
        fprintf(stderr, "qemu: could not load kernel '%s'\n",
                info->kernel_filename);
        exit(1);
    }
    info->entry = entry;
    if (is_linux) {
        uint32_t fixupcontext[FIXUP_MAX];

        if (info->initrd_filename) {
            initrd_size = load_ramdisk(info->initrd_filename,
                                       info->initrd_start,
                                       info->ram_size -
                                       info->initrd_start);
            if (initrd_size < 0) {
                initrd_size = load_image_targphys(info->initrd_filename,
                                                  info->initrd_start,
                                                  info->ram_size -
                                                  info->initrd_start);
            }
            if (initrd_size < 0) {
                fprintf(stderr, "qemu: could not load initrd '%s'\n",
                        info->initrd_filename);
                exit(1);
            }
        } else {
            initrd_size = 0;
        }
        info->initrd_size = initrd_size;

        fixupcontext[FIXUP_BOARDID] = info->board_id;

        /* for device tree boot, we pass the DTB directly in r2. Otherwise
         * we point to the kernel args.
         */
        if (have_dtb(info)) {
            /* Place the DTB after the initrd in memory. Note that some
             * kernels will trash anything in the 4K page the initrd
             * ends in, so make sure the DTB isn't caught up in that.
             */
            hwaddr dtb_start = QEMU_ALIGN_UP(info->initrd_start + initrd_size,
                                             4096);
            if (load_dtb(dtb_start, info, 0) < 0) {
                exit(1);
            }
            fixupcontext[FIXUP_ARGPTR] = dtb_start;
        } else {
            fixupcontext[FIXUP_ARGPTR] = info->loader_start + KERNEL_ARGS_ADDR;
            if (info->ram_size >= (1ULL << 32)) {
                fprintf(stderr, "qemu: RAM size must be less than 4GB to boot"
                        " Linux kernel using ATAGS (try passing a device tree"
                        " using -dtb)\n");
                exit(1);
            }
        }
        fixupcontext[FIXUP_ENTRYPOINT] = entry;

        write_bootloader("bootloader", info->loader_start,
                         primary_loader, fixupcontext);

        if (info->nb_cpus > 1) {
            info->write_secondary_boot(cpu, info);
        }
    }
    info->is_linux = is_linux;

    for (cs = CPU(cpu); cs; cs = CPU_NEXT(cs)) {
        ARM_CPU(cs)->env.boot_info = info;
    }
}