Re: [Qemu-devel] [RFC][PATCH 08/14 v4] introduce a new monitor command 'dump' to dump guest's memory

[Luiz Capitulino]

On Wed, 04 Jan 2012 14:11:01 +0800
Wen Congyang <address@hidden> wrote:

> Signed-off-by: Wen Congyang <address@hidden>
> ---
>  Makefile.target |    8 +-
>  dump.c          |  588 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  dump.h          |    4 +
>  hmp-commands.hx |   16 ++
>  monitor.c       |    3 +
>  qmp-commands.hx |   26 +++
>  6 files changed, 641 insertions(+), 4 deletions(-)
>  create mode 100644 dump.c
> 
> diff --git a/Makefile.target b/Makefile.target
> index 29562ad..f7cc2b9 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -110,7 +110,7 @@ $(call set-vpath, 
> $(SRC_PATH)/linux-user:$(SRC_PATH)/linux-user/$(TARGET_ABI_DIR
>  QEMU_CFLAGS+=-I$(SRC_PATH)/linux-user/$(TARGET_ABI_DIR) 
> -I$(SRC_PATH)/linux-user
>  obj-y = main.o syscall.o strace.o mmap.o signal.o thunk.o \
>        elfload.o linuxload.o uaccess.o gdbstub.o cpu-uname.o \
> -      user-exec.o $(oslib-obj-y)
> +      user-exec.o $(oslib-obj-y) dump.o
>  
>  obj-$(TARGET_HAS_BFLT) += flatload.o
>  
> @@ -148,7 +148,7 @@ LDFLAGS+=-Wl,-segaddr,__STD_PROG_ZONE,0x1000 -image_base 
> 0x0e000000
>  LIBS+=-lmx
>  
>  obj-y = main.o commpage.o machload.o mmap.o signal.o syscall.o thunk.o \
> -        gdbstub.o user-exec.o
> +        gdbstub.o user-exec.o dump.o
>  
>  obj-i386-y += ioport-user.o
>  
> @@ -170,7 +170,7 @@ $(call set-vpath, $(SRC_PATH)/bsd-user)
>  QEMU_CFLAGS+=-I$(SRC_PATH)/bsd-user -I$(SRC_PATH)/bsd-user/$(TARGET_ARCH)
>  
>  obj-y = main.o bsdload.o elfload.o mmap.o signal.o strace.o syscall.o \
> -        gdbstub.o uaccess.o user-exec.o
> +        gdbstub.o uaccess.o user-exec.o dump.o
>  
>  obj-i386-y += ioport-user.o
>  
> @@ -186,7 +186,7 @@ endif #CONFIG_BSD_USER
>  # System emulator target
>  ifdef CONFIG_SOFTMMU
>  
> -obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o balloon.o ioport.o
> +obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o balloon.o ioport.o 
> dump.o
>  # virtio has to be here due to weird dependency between PCI and virtio-net.
>  # need to fix this properly
>  obj-$(CONFIG_NO_PCI) += pci-stub.o
> diff --git a/dump.c b/dump.c
> new file mode 100644
> index 0000000..ab29a4c
> --- /dev/null
> +++ b/dump.c
> @@ -0,0 +1,588 @@
> +/*
> + * QEMU dump
> + *
> + * Copyright Fujitsu, Corp. 2011
> + *
> + * Authors:
> + *     Wen Congyang <address@hidden>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.  See
> + * the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu-common.h"
> +#include <unistd.h>
> +#include <elf.h>
> +#include <sys/procfs.h>
> +#include "cpu.h"
> +#include "cpu-all.h"
> +#include "targphys.h"
> +#include "monitor.h"
> +#include "kvm.h"
> +#include "dump.h"
> +#include "sysemu.h"
> +#include "bswap.h"
> +#include "memory_mapping.h"
> +
> +#define CPU_CONVERT_TO_TARGET16(val) \
> +({ \
> +    uint16_t _val = (val); \
> +    if (endian == ELFDATA2LSB) { \
> +        _val = cpu_to_le16(_val); \
> +    } else {\
> +        _val = cpu_to_be16(_val); \
> +    } \
> +    _val; \
> +})
> +
> +#define CPU_CONVERT_TO_TARGET32(val) \
> +({ \
> +    uint32_t _val = (val); \
> +    if (endian == ELFDATA2LSB) { \
> +        _val = cpu_to_le32(_val); \
> +    } else {\
> +        _val = cpu_to_be32(_val); \
> +    } \
> +    _val; \
> +})
> +
> +#define CPU_CONVERT_TO_TARGET64(val) \
> +({ \
> +    uint64_t _val = (val); \
> +    if (endian == ELFDATA2LSB) { \
> +        _val = cpu_to_le64(_val); \
> +    } else {\
> +        _val = cpu_to_be64(_val); \
> +    } \
> +    _val; \
> +})
> +
> +enum {
> +    DUMP_STATE_ERROR,
> +    DUMP_STATE_SETUP,
> +    DUMP_STATE_CANCELLED,
> +    DUMP_STATE_ACTIVE,
> +    DUMP_STATE_COMPLETED,
> +};
> +
> +typedef struct DumpState {
> +    ArchDumpInfo dump_info;
> +    MemoryMappingList list;
> +    int phdr_num;
> +    int state;
> +    char *error;
> +    Monitor *mon;
> +    int fd;
> +    target_phys_addr_t memory_offset;
> +} DumpState;
> +
> +static DumpState *dump_get_current(void)
> +{
> +    static DumpState current_dump = {
> +        .state = DUMP_STATE_SETUP,
> +    };
> +
> +    return &current_dump;
> +}
> +
> +static int dump_cleanup(DumpState *s)
> +{
> +    int ret = 0;
> +
> +    free_memory_mapping_list(&s->list);
> +    if (s->fd != -1) {
> +        close(s->fd);
> +        s->fd = -1;
> +    }
> +
> +    return ret;
> +}
> +
> +static void dump_error(DumpState *s, const char *reason)
> +{
> +    s->state = DUMP_STATE_ERROR;
> +    s->error = g_strdup(reason);
> +    dump_cleanup(s);
> +}
> +
> +static inline int cpuid(CPUState *env)
> +{
> +#if defined(CONFIG_USER_ONLY) && defined(CONFIG_USE_NPTL)
> +    return env->host_tid;
> +#else
> +    return env->cpu_index + 1;
> +#endif
> +}
> +
> +static int write_elf64_header(DumpState *s)
> +{
> +    Elf64_Ehdr elf_header;
> +    int ret;
> +    int endian = s->dump_info.d_endian;
> +
> +    memset(&elf_header, 0, sizeof(Elf64_Ehdr));
> +    memcpy(&elf_header, ELFMAG, 4);
> +    elf_header.e_ident[EI_CLASS] = ELFCLASS64;
> +    elf_header.e_ident[EI_DATA] = s->dump_info.d_endian;
> +    elf_header.e_ident[EI_VERSION] = EV_CURRENT;
> +    elf_header.e_type = CPU_CONVERT_TO_TARGET16(ET_CORE);
> +    elf_header.e_machine = CPU_CONVERT_TO_TARGET16(s->dump_info.d_machine);
> +    elf_header.e_version = CPU_CONVERT_TO_TARGET32(EV_CURRENT);
> +    elf_header.e_ehsize = CPU_CONVERT_TO_TARGET16(sizeof(elf_header));
> +    elf_header.e_phoff = CPU_CONVERT_TO_TARGET64(sizeof(Elf64_Ehdr));
> +    elf_header.e_phentsize = CPU_CONVERT_TO_TARGET16(sizeof(Elf64_Phdr));
> +    elf_header.e_phnum = CPU_CONVERT_TO_TARGET16(s->phdr_num);
> +
> +    lseek(s->fd, 0, SEEK_SET);
> +    ret = write(s->fd, &elf_header, sizeof(elf_header));
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to write elf header.\n");
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int write_elf32_header(DumpState *s)
> +{
> +    Elf32_Ehdr elf_header;
> +    int ret;
> +    int endian = s->dump_info.d_endian;
> +
> +    memset(&elf_header, 0, sizeof(Elf32_Ehdr));
> +    memcpy(&elf_header, ELFMAG, 4);
> +    elf_header.e_ident[EI_CLASS] = ELFCLASS32;
> +    elf_header.e_ident[EI_DATA] = endian;
> +    elf_header.e_ident[EI_VERSION] = EV_CURRENT;
> +    elf_header.e_type = CPU_CONVERT_TO_TARGET16(ET_CORE);
> +    elf_header.e_machine = CPU_CONVERT_TO_TARGET16(s->dump_info.d_machine);
> +    elf_header.e_version = CPU_CONVERT_TO_TARGET32(EV_CURRENT);
> +    elf_header.e_ehsize = CPU_CONVERT_TO_TARGET16(sizeof(elf_header));
> +    elf_header.e_phoff = CPU_CONVERT_TO_TARGET32(sizeof(Elf32_Ehdr));
> +    elf_header.e_phentsize = CPU_CONVERT_TO_TARGET16(sizeof(Elf32_Phdr));
> +    elf_header.e_phnum = CPU_CONVERT_TO_TARGET16(s->phdr_num);
> +
> +    lseek(s->fd, 0, SEEK_SET);
> +    ret = write(s->fd, &elf_header, sizeof(elf_header));
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to write elf header.\n");
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
> +                            int phdr_index, target_phys_addr_t offset)
> +{
> +    Elf64_Phdr phdr;
> +    off_t phdr_offset;
> +    int ret;
> +    int endian = s->dump_info.d_endian;
> +
> +    memset(&phdr, 0, sizeof(Elf64_Phdr));
> +    phdr.p_type = CPU_CONVERT_TO_TARGET32(PT_LOAD);
> +    phdr.p_offset = CPU_CONVERT_TO_TARGET64(offset);
> +    phdr.p_paddr = CPU_CONVERT_TO_TARGET64(memory_mapping->phys_addr);
> +    if (offset == -1) {
> +        phdr.p_filesz = 0;
> +    } else {
> +        phdr.p_filesz = CPU_CONVERT_TO_TARGET64(memory_mapping->length);
> +    }
> +    phdr.p_memsz = CPU_CONVERT_TO_TARGET64(memory_mapping->length);
> +    phdr.p_vaddr = CPU_CONVERT_TO_TARGET64(memory_mapping->virt_addr);
> +
> +    phdr_offset = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr)*phdr_index;
> +    lseek(s->fd, phdr_offset, SEEK_SET);
> +    ret = write(s->fd, &phdr, sizeof(Elf64_Phdr));
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to write program header table.\n");
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
> +                            int phdr_index, target_phys_addr_t offset)
> +{
> +    Elf32_Phdr phdr;
> +    off_t phdr_offset;
> +    int ret;
> +    int endian = s->dump_info.d_endian;
> +
> +    memset(&phdr, 0, sizeof(Elf32_Phdr));
> +    phdr.p_type = CPU_CONVERT_TO_TARGET32(PT_LOAD);
> +    phdr.p_offset = CPU_CONVERT_TO_TARGET32(offset);
> +    phdr.p_paddr = CPU_CONVERT_TO_TARGET32(memory_mapping->phys_addr);
> +    if (offset == -1) {
> +        phdr.p_filesz = 0;
> +    } else {
> +        phdr.p_filesz = CPU_CONVERT_TO_TARGET32(memory_mapping->length);
> +    }
> +    phdr.p_memsz = CPU_CONVERT_TO_TARGET32(memory_mapping->length);
> +    phdr.p_vaddr = CPU_CONVERT_TO_TARGET32(memory_mapping->virt_addr);
> +
> +    phdr_offset = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr)*phdr_index;
> +    lseek(s->fd, phdr_offset, SEEK_SET);
> +    ret = write(s->fd, &phdr, sizeof(Elf32_Phdr));
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to write program header table.\n");
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int write_elf64_notes(DumpState *s, int phdr_index,
> +                             target_phys_addr_t *offset)
> +{
> +    CPUState *env;
> +    int ret;
> +    target_phys_addr_t begin = *offset;
> +    Elf64_Phdr phdr;
> +    off_t phdr_offset;
> +    int id;
> +    int endian = s->dump_info.d_endian;
> +
> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
> +        id = cpuid(env);
> +        ret = cpu_write_elf64_note(s->fd, env, id, offset);
> +        if (ret < 0) {
> +            dump_error(s, "dump: failed to write elf notes.\n");
> +            return -1;
> +        }
> +    }
> +
> +    memset(&phdr, 0, sizeof(Elf64_Phdr));
> +    phdr.p_type = CPU_CONVERT_TO_TARGET32(PT_NOTE);
> +    phdr.p_offset = CPU_CONVERT_TO_TARGET64(begin);
> +    phdr.p_paddr = 0;
> +    phdr.p_filesz = CPU_CONVERT_TO_TARGET64(*offset - begin);
> +    phdr.p_memsz = CPU_CONVERT_TO_TARGET64(*offset - begin);
> +    phdr.p_vaddr = 0;
> +
> +    phdr_offset = sizeof(Elf64_Ehdr);
> +    lseek(s->fd, phdr_offset, SEEK_SET);
> +    ret = write(s->fd, &phdr, sizeof(Elf64_Phdr));
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to write program header table.\n");
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int write_elf32_notes(DumpState *s, int phdr_index,
> +                             target_phys_addr_t *offset)
> +{
> +    CPUState *env;
> +    int ret;
> +    target_phys_addr_t begin = *offset;
> +    Elf32_Phdr phdr;
> +    off_t phdr_offset;
> +    int id;
> +    int endian = s->dump_info.d_endian;
> +
> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
> +        id = cpuid(env);
> +        ret = cpu_write_elf32_note(s->fd, env, id, offset);
> +        if (ret < 0) {
> +            dump_error(s, "dump: failed to write elf notes.\n");
> +            return -1;
> +        }
> +    }
> +
> +    memset(&phdr, 0, sizeof(Elf32_Phdr));
> +    phdr.p_type = CPU_CONVERT_TO_TARGET32(PT_NOTE);
> +    phdr.p_offset = CPU_CONVERT_TO_TARGET32(begin);
> +    phdr.p_paddr = 0;
> +    phdr.p_filesz = CPU_CONVERT_TO_TARGET32(*offset - begin);
> +    phdr.p_memsz = CPU_CONVERT_TO_TARGET32(*offset - begin);
> +    phdr.p_vaddr = 0;
> +
> +    phdr_offset = sizeof(Elf32_Ehdr);
> +    lseek(s->fd, phdr_offset, SEEK_SET);
> +    ret = write(s->fd, &phdr, sizeof(Elf32_Phdr));
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to write program header table.\n");
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int write_data(DumpState *s, void *buf, int length,
> +                      target_phys_addr_t *offset)
> +{
> +    int ret;
> +
> +    lseek(s->fd, *offset, SEEK_SET);
> +    ret = write(s->fd, buf, length);
> +    if (ret < 0) {
> +        dump_error(s, "dump: failed to save memory.\n");
> +        return -1;
> +    }
> +
> +    *offset += length;
> +    return 0;
> +}
> +
> +/* write the memroy to vmcore. 1 page per I/O. */
> +static int write_memory(DumpState *s, RAMBlock *block,
> +                        target_phys_addr_t *offset)
> +{
> +    int i, ret;
> +
> +    for (i = 0; i < block->length / TARGET_PAGE_SIZE; i++) {
> +        ret = write_data(s, block->host + i * TARGET_PAGE_SIZE,
> +                         TARGET_PAGE_SIZE, offset);
> +        if (ret < 0) {
> +            return -1;
> +        }
> +    }
> +
> +    if ((block->length % TARGET_PAGE_SIZE) != 0) {
> +        ret = write_data(s, block->host + i * TARGET_PAGE_SIZE,
> +                         block->length % TARGET_PAGE_SIZE, offset);
> +        if (ret < 0) {
> +            return -1;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +/* get the memory's offset in the vmcore */
> +static target_phys_addr_t get_offset(target_phys_addr_t phys_addr,
> +                                     target_phys_addr_t memory_offset)
> +{
> +    RAMBlock *block;
> +    target_phys_addr_t offset = memory_offset;
> +
> +    QLIST_FOREACH(block, &ram_list.blocks, next) {
> +        if (phys_addr >= block->offset &&
> +            phys_addr < block->offset + block->length) {
> +            return phys_addr - block->offset + offset;
> +        }
> +        offset += block->length;
> +    }
> +
> +    return -1;
> +}
> +
> +static DumpState *dump_init(Monitor *mon, int fd)
> +{
> +    CPUState *env;
> +    DumpState *s = dump_get_current();
> +    int ret;
> +
> +    vm_stop(RUN_STATE_PAUSED);
> +    s->state = DUMP_STATE_SETUP;
> +    s->error = NULL;
> +    s->mon = mon;
> +    s->fd = fd;
> +
> +    /*
> +     * get dump info: endian, class and architecture.
> +     * If the target architecture is not supported, cpu_get_dump_info() will
> +     * return -1.
> +     *
> +     * if we use kvm, we should synchronize the register before we get dump
> +     * info.
> +     */
> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
> +        cpu_synchronize_state(env);
> +    }
> +    ret = cpu_get_dump_info(&s->dump_info);
> +    if (ret < 0) {
> +        monitor_printf(mon, "dump: unsupported target.\n");
> +        return NULL;
> +    }
> +
> +    /* get memory mapping */
> +    s->list.num = 0;
> +    QTAILQ_INIT(&s->list.head);
> +    get_memory_mapping(&s->list);
> +
> +    /* crash needs extra memory mapping to determine phys_base. */
> +    ret = cpu_add_extra_memory_mapping(&s->list);
> +    if (ret < 0) {
> +        monitor_printf(mon, "dump: failed to add extra memory mapping.\n");
> +        return NULL;
> +    }
> +
> +    /*
> +     * calculate phdr_num
> +     *
> +     * the type of phdr->num is uint16_t, so we should avoid overflow
> +     */
> +    s->phdr_num = 1; /* PT_NOTE */
> +    if (s->list.num > (1 << 16) - 2) {
> +        s->phdr_num = (1 << 16) - 1;
> +    } else {
> +        s->phdr_num += s->list.num;
> +    }
> +
> +    return s;
> +}
> +
> +/* write elf header, PT_NOTE and elf note to vmcore. */
> +static int dump_begin(DumpState *s)
> +{
> +    target_phys_addr_t offset;
> +    int ret;
> +
> +    s->state = DUMP_STATE_ACTIVE;
> +
> +    /*
> +     * the vmcore's format is:
> +     *   --------------
> +     *   |  elf header |
> +     *   --------------
> +     *   |  PT_NOTE    |
> +     *   --------------
> +     *   |  PT_LOAD    |
> +     *   --------------
> +     *   |  ......     |
> +     *   --------------
> +     *   |  PT_LOAD    |
> +     *   --------------
> +     *   |  elf note   |
> +     *   --------------
> +     *   |  memory     |
> +     *   --------------
> +     *
> +     * we only know where the memory is saved after we write elf note into
> +     * vmcore.
> +     */
> +
> +    /* write elf header to vmcore */
> +    if (s->dump_info.d_class == ELFCLASS64) {
> +        ret = write_elf64_header(s);
> +    } else {
> +        ret = write_elf32_header(s);
> +    }
> +    if (ret < 0) {
> +        return -1;
> +    }
> +
> +    /* write elf notes to vmcore */
> +    if (s->dump_info.d_class == ELFCLASS64) {
> +        offset = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr)*s->phdr_num;
> +        ret = write_elf64_notes(s, 0, &offset);
> +    } else {
> +        offset = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr)*s->phdr_num;
> +        ret = write_elf32_notes(s, 0, &offset);
> +    }
> +
> +    if (ret < 0) {
> +        return -1;
> +    }
> +
> +    s->memory_offset = offset;
> +    return 0;
> +}
> +
> +/* write PT_LOAD to vmcore */
> +static int dump_completed(DumpState *s)
> +{
> +    target_phys_addr_t offset;
> +    MemoryMapping *memory_mapping;
> +    int phdr_index = 1, ret;
> +
> +    QTAILQ_FOREACH(memory_mapping, &s->list.head, next) {
> +        offset = get_offset(memory_mapping->phys_addr, s->memory_offset);
> +        if (s->dump_info.d_class == ELFCLASS64) {
> +            ret = write_elf64_load(s, memory_mapping, phdr_index++, offset);
> +        } else {
> +            ret = write_elf32_load(s, memory_mapping, phdr_index++, offset);
> +        }
> +        if (ret < 0) {
> +            return -1;
> +        }
> +    }
> +
> +    s->state = DUMP_STATE_COMPLETED;
> +    dump_cleanup(s);
> +    return 0;
> +}
> +
> +/* write all memory to vmcore */
> +static int dump_iterate(DumpState *s)
> +{
> +    RAMBlock *block;
> +    target_phys_addr_t offset = s->memory_offset;
> +    int ret;
> +
> +    /* write all memory to vmcore */
> +    QLIST_FOREACH(block, &ram_list.blocks, next) {
> +        ret = write_memory(s, block, &offset);
> +        if (ret < 0) {
> +            return -1;
> +        }
> +    }
> +
> +    return dump_completed(s);
> +}
> +
> +static int create_vmcore(DumpState *s)
> +{
> +    int ret;
> +
> +    ret = dump_begin(s);
> +    if (ret < 0) {
> +        return -1;
> +    }
> +
> +    ret = dump_iterate(s);
> +    if (ret < 0) {
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +int do_dump(Monitor *mon, const QDict *qdict, QObject **ret_data)

This is not using the QAPI. Please, take a look at the document
docs/writing-qmp-commands.txt on how to do that. You can also look at the
various examples in hmp.c/qmp.c.

I haven't reviewed your approach for the asynchronous support yet. We're
discussing right now what to do wrt commands introducing their own async
support, will review it as soon as we have a decision.

Btw, I'd like to have an ack from Jan for the general approach of this
command.

> +{
> +    const char *file = qdict_get_str(qdict, "file");
> +    const char *p;
> +    int fd = -1;
> +    DumpState *s;
> +
> +#if !defined(WIN32)
> +    if (strstart(file, "fd:", &p)) {
> +        fd = monitor_get_fd(mon, p);
> +        if (fd == -1) {
> +            monitor_printf(mon, "dump: invalid file descriptor"
> +                           " identifier\n");
> +            return -1;
> +        }
> +    }
> +#endif
> +
> +    if  (strstart(file, "file:", &p)) {
> +        fd = open(p, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY);
> +        if (fd < 0) {
> +            monitor_printf(mon, "dump: failed to open %s\n", p);
> +            return -1;
> +        }
> +    }
> +
> +    if (fd == -1) {
> +        monitor_printf(mon, "unknown dump protocol: %s\n", file);
> +        return -1;
> +    }
> +
> +    s = dump_init(mon, fd);
> +    if (!s) {
> +        return -1;
> +    }
> +
> +    if (create_vmcore(s) < 0) {
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> diff --git a/dump.h b/dump.h
> index a36468b..def6c0e 100644
> --- a/dump.h
> +++ b/dump.h
> @@ -1,10 +1,14 @@
>  #ifndef DUMP_H
>  #define DUMP_H
>  
> +#include "qdict.h"
> +
>  typedef struct ArchDumpInfo {
>      int d_machine;  /* Architecture */
>      int d_endian;   /* ELFDATA2LSB or ELFDATA2MSB */
>      int d_class;    /* ELFCLASS32 or ELFCLASS64 */
>  } ArchDumpInfo;
>  
> +int do_dump(Monitor *mon, const QDict *qdict, QObject **ret_data);
> +
>  #endif
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 14838b7..98c1c35 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -828,6 +828,22 @@ new parameters (if specified) once the vm migration 
> finished successfully.
>  ETEXI
>  
>      {
> +        .name       = "dump",
> +        .args_type  = "file:s",
> +        .params     = "file",
> +        .help       = "dump to file",
> +        .user_print = monitor_user_noop,
> +        .mhandler.cmd_new = do_dump,
> +    },
> +
> +
> +STEXI
> address@hidden dump @var{file}
> address@hidden dump
> +Dump to @var{file}.
> +ETEXI
> +
> +    {
>          .name       = "snapshot_blkdev",
>          .args_type  = "device:B,snapshot-file:s?,format:s?",
>          .params     = "device [new-image-file] [format]",
> diff --git a/monitor.c b/monitor.c
> index 7334401..edd6aa7 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -73,6 +73,9 @@
>  #endif
>  #include "hw/lm32_pic.h"
>  
> +/* for dump */
> +#include "dump.h"
> +
>  //#define DEBUG
>  //#define DEBUG_COMPLETION
>  
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 7e3f4b9..023cade 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -572,6 +572,32 @@ Example:
>  EQMP
>  
>      {
> +        .name       = "dump",
> +        .args_type  = "file:s",
> +        .params     = "file",
> +        .help       = "dump to file",
> +        .user_print = monitor_user_noop,
> +        .mhandler.cmd_new = do_dump,
> +    },
> +
> +SQMP
> +dump
> +
> +
> +Dump to file.
> +
> +Arguments:
> +
> +- "file": Destination file (json-string)
> +
> +Example:
> +
> +-> { "execute": "dump", "arguments": { "file": "fd:dump" } }
> +<- { "return": {} }
> +
> +EQMP
> +
> +    {
>          .name       = "netdev_add",
>          .args_type  = "netdev:O",
>          .params     = "[user|tap|socket],id=str[,prop=value][,...]",