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

[Luiz Capitulino]

On Wed, 11 Jan 2012 08:59:24 +0800
Wen Congyang <address@hidden> wrote:

> At 01/10/2012 09:30 PM, Luiz Capitulino Wrote:
> > 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.
> 
> Yes, I have read it. But I need monitor to get fd, and I do not find such
> examples. The command migrate also needs fd, and it is not converted to use
> the QAPI. So, I do not know how to do that.

I have a first try on converting the migrate command to the QAPI in
this branch:

 
http://repo.or.cz/w/qemu/qmp-unstable.git/shortlog/refs/heads/qmp-wip/qapi-commands-conv/set-complex/v1

I guess all you need is the qemu_get_fd() function.

> 
> Thanks
> Wen Congyang
> 
> > 
> > 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][,...]",
> > 
> > 
>