Re: [PATCH v36 01/17] target/avr: Add outward facing interfaces and core CPU logic

[Aleksandar Markovic]

On Sunday, November 24, 2019, Michael Rolnik <address@hidden> wrote:
> This includes:
> - CPU data structures
> - object model classes and functions
> - migration functions
> - GDB hooks
>
> Co-developed-by: Michael Rolnik <address@hidden>
> Co-developed-by: Sarah Harris <address@hidden>
> Signed-off-by: Michael Rolnik <address@hidden>
> Signed-off-by: Sarah Harris <address@hidden>
> Signed-off-by: Michael Rolnik <address@hidden>
> Acked-by: Igor Mammedov <address@hidden>
> ---

Unfortunately, it appears to me that support for AVR-specific gdb command "info io_registers" is missing. This command looks very important in overall AVR/gdb context, and I think we shouldn't leave it unsupported. (please prove me wrong if I am mistaken here in any way).

Cc- ing Alex as he is the maintainer for gdbstub QEMU component, for his opinion and advice.

Philippe, what happens in your experimental AVR setups, if the gdb command  "info io_registers" is used?

Aleksandar

From gdb docs:

21.3.8 Atmel AVR

When configured for debugging the Atmel AVR, GDB supports the following AVR-specific commands:

info io_registers

This command displays information about the AVR I/O registers. For each register, GDB prints its number and value.

 

>  target/avr/cpu-param.h |  37 +++
>  target/avr/cpu-qom.h   |  54 ++++
>  target/avr/cpu.h       | 253 ++++++++++++++++++
>  target/avr/cpu.c       | 576 +++++++++++++++++++++++++++++++++++++++++
>  target/avr/gdbstub.c   |  85 ++++++
>  target/avr/machine.c   | 121 +++++++++
>  gdb-xml/avr-cpu.xml    |  49 ++++
>  7 files changed, 1175 insertions(+)
>  create mode 100644 target/avr/cpu-param.h
>  create mode 100644 target/avr/cpu-qom.h
>  create mode 100644 target/avr/cpu.h
>  create mode 100644 target/avr/cpu.c
>  create mode 100644 target/avr/gdbstub.c
>  create mode 100644 target/avr/machine.c
>  create mode 100644 gdb-xml/avr-cpu.xml
>
> diff --git a/target/avr/cpu-param.h b/target/avr/cpu-param.h
> new file mode 100644
> index 0000000000..ccd1ea3429
> --- /dev/null
> +++ b/target/avr/cpu-param.h
> @@ -0,0 +1,37 @@
> +/*
> + * QEMU AVR CPU
> + *
> + * Copyright (c) 2019 Michael Rolnik
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> + * <http://www.gnu.org/licenses/lgpl-2.1.html>
> + */
> +
> +#ifndef AVR_CPU_PARAM_H
> +#define AVR_CPU_PARAM_H 1
> +
> +#define TARGET_LONG_BITS 32
> +/*
> + * TARGET_PAGE_BITS cannot be more than 8 bits because
> + * 1.  all IO registers occupy [0x0000 .. 0x00ff] address range, and they
> + *     should be implemented as a device and not memory
> + * 2.  SRAM starts at the address 0x0100
> + */
> +#define TARGET_PAGE_BITS 8
> +#define TARGET_PHYS_ADDR_SPACE_BITS 24
> +#define TARGET_VIRT_ADDR_SPACE_BITS 24
> +#define NB_MMU_MODES 2
> +
> +
> +#endif
> diff --git a/target/avr/cpu-qom.h b/target/avr/cpu-qom.h
> new file mode 100644
> index 0000000000..e28b58c897
> --- /dev/null
> +++ b/target/avr/cpu-qom.h
> @@ -0,0 +1,54 @@
> +/*
> + * QEMU AVR CPU
> + *
> + * Copyright (c) 2019 Michael Rolnik
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> + * <http://www.gnu.org/licenses/lgpl-2.1.html>
> + */
> +
> +#ifndef QEMU_AVR_QOM_H
> +#define QEMU_AVR_QOM_H
> +
> +#include "hw/core/cpu.h"
> +
> +#define TYPE_AVR_CPU "avr-cpu"
> +
> +#define AVR_CPU_CLASS(klass) \
> +    OBJECT_CLASS_CHECK(AVRCPUClass, (klass), TYPE_AVR_CPU)
> +#define AVR_CPU(obj) \
> +    OBJECT_CHECK(AVRCPU, (obj), TYPE_AVR_CPU)
> +#define AVR_CPU_GET_CLASS(obj) \
> +    OBJECT_GET_CLASS(AVRCPUClass, (obj), TYPE_AVR_CPU)
> +
> +/**
> + *  AVRCPUClass:
> + *  @parent_realize: The parent class' realize handler.
> + *  @parent_reset: The parent class' reset handler.
> + *  @vr: Version Register value.
> + *
> + *  A AVR CPU model.
> + */
> +typedef struct AVRCPUClass {
> +    /*< private >*/
> +    CPUClass parent_class;
> +    /*< public >*/
> +    DeviceRealize parent_realize;
> +    void (*parent_reset)(CPUState *cpu);
> +} AVRCPUClass;
> +
> +typedef struct AVRCPU AVRCPU;
> +
> +
> +#endif /* !defined (QEMU_AVR_CPU_QOM_H) */
> diff --git a/target/avr/cpu.h b/target/avr/cpu.h
> new file mode 100644
> index 0000000000..ed9218af5f
> --- /dev/null
> +++ b/target/avr/cpu.h
> @@ -0,0 +1,253 @@
> +/*
> + * QEMU AVR CPU
> + *
> + * Copyright (c) 2019 Michael Rolnik
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> + * <http://www.gnu.org/licenses/lgpl-2.1.html>
> + */
> +
> +#ifndef QEMU_AVR_CPU_H
> +#define QEMU_AVR_CPU_H
> +
> +#include "cpu-qom.h"
> +#include "exec/cpu-defs.h"
> +
> +#define TCG_GUEST_DEFAULT_MO 0
> +
> +#define CPU_RESOLVING_TYPE TYPE_AVR_CPU
> +
> +/*
> + * AVR has two memory spaces, data & code.
> + * e.g. both have 0 address
> + * ST/LD instructions access data space
> + * LPM/SPM and instruction fetching access code memory space
> + */
> +#define MMU_CODE_IDX 0
> +#define MMU_DATA_IDX 1
> +
> +#define EXCP_RESET 1
> +#define EXCP_INT(n) (EXCP_RESET + (n) + 1)
> +
> +/* Number of CPU registers */
> +#define NO_CPU_REGISTERS 32
> +/* Number of IO registers accessible by ld/st/in/out */
> +#define NO_IO_REGISTERS 64
> +
> +/*
> + * Offsets of AVR memory regions in host memory space.
> + *
> + * This is needed because the AVR has separate code and data address
> + * spaces that both have start from zero but have to go somewhere in
> + * host memory.
> + *
> + * It's also useful to know where some things are, like the IO registers.
> + */
> +/* Flash program memory */
> +#define OFFSET_CODE 0x00000000
> +/* CPU registers, IO registers, and SRAM */
> +#define OFFSET_DATA 0x00800000
> +/* CPU registers specifically, these are mapped at the start of data */
> +#define OFFSET_CPU_REGISTERS OFFSET_DATA
> +/*
> + * IO registers, including status register, stack pointer, and memory
> + * mapped peripherals, mapped just after CPU registers
> + */
> +#define OFFSET_IO_REGISTERS (OFFSET_DATA + NO_CPU_REGISTERS)
> +
> +enum avr_features {
> +    AVR_FEATURE_SRAM,
> +
> +    AVR_FEATURE_1_BYTE_PC,
> +    AVR_FEATURE_2_BYTE_PC,
> +    AVR_FEATURE_3_BYTE_PC,
> +
> +    AVR_FEATURE_1_BYTE_SP,
> +    AVR_FEATURE_2_BYTE_SP,
> +
> +    AVR_FEATURE_BREAK,
> +    AVR_FEATURE_DES,
> +    AVR_FEATURE_RMW, /* Read Modify Write - XCH LAC LAS LAT */
> +
> +    AVR_FEATURE_EIJMP_EICALL,
> +    AVR_FEATURE_IJMP_ICALL,
> +    AVR_FEATURE_JMP_CALL,
> +
> +    AVR_FEATURE_ADIW_SBIW,
> +
> +    AVR_FEATURE_SPM,
> +    AVR_FEATURE_SPMX,
> +
> +    AVR_FEATURE_ELPMX,
> +    AVR_FEATURE_ELPM,
> +    AVR_FEATURE_LPMX,
> +    AVR_FEATURE_LPM,
> +
> +    AVR_FEATURE_MOVW,
> +    AVR_FEATURE_MUL,
> +    AVR_FEATURE_RAMPD,
> +    AVR_FEATURE_RAMPX,
> +    AVR_FEATURE_RAMPY,
> +    AVR_FEATURE_RAMPZ,
> +};
> +
> +typedef struct CPUAVRState CPUAVRState;
> +
> +struct CPUAVRState {
> +    uint32_t pc_w; /* 0x003fffff up to 22 bits */
> +
> +    uint32_t sregC; /* 0x00000001 1 bit */
> +    uint32_t sregZ; /* 0x00000001 1 bit */
> +    uint32_t sregN; /* 0x00000001 1 bit */
> +    uint32_t sregV; /* 0x00000001 1 bit */
> +    uint32_t sregS; /* 0x00000001 1 bit */
> +    uint32_t sregH; /* 0x00000001 1 bit */
> +    uint32_t sregT; /* 0x00000001 1 bit */
> +    uint32_t sregI; /* 0x00000001 1 bit */
> +
> +    uint32_t rampD; /* 0x00ff0000 8 bits */
> +    uint32_t rampX; /* 0x00ff0000 8 bits */
> +    uint32_t rampY; /* 0x00ff0000 8 bits */
> +    uint32_t rampZ; /* 0x00ff0000 8 bits */
> +    uint32_t eind; /* 0x00ff0000 8 bits */
> +
> +    uint32_t r[NO_CPU_REGISTERS]; /* 8 bits each */
> +    uint32_t sp; /* 16 bits */
> +
> +    uint32_t skip; /* if set skip instruction */
> +
> +    uint64_t intsrc; /* interrupt sources */
> +    bool fullacc; /* CPU/MEM if true MEM only otherwise */
> +
> +    uint32_t features;
> +};
> +
> +/**
> + *  AVRCPU:
> + *  @env: #CPUAVRState
> + *
> + *  A AVR CPU.
> + */
> +typedef struct AVRCPU {
> +    /*< private >*/
> +    CPUState parent_obj;
> +    /*< public >*/
> +
> +    CPUNegativeOffsetState neg;
> +    CPUAVRState env;
> +} AVRCPU;
> +
> +#ifndef CONFIG_USER_ONLY
> +extern const struct VMStateDescription vms_avr_cpu;
> +#endif
> +
> +void avr_cpu_do_interrupt(CPUState *cpu);
> +bool avr_cpu_exec_interrupt(CPUState *cpu, int int_req);
> +hwaddr avr_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
> +int avr_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
> +int avr_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
> +
> +static inline int avr_feature(CPUAVRState *env, int feature)
> +{
> +    return (env->features & (1U << feature)) != 0;
> +}
> +
> +static inline void avr_set_feature(CPUAVRState *env, int feature)
> +{
> +    env->features |= (1U << feature);
> +}
> +
> +#define cpu_list avr_cpu_list
> +#define cpu_signal_handler cpu_avr_signal_handler
> +#define cpu_mmu_index avr_cpu_mmu_index
> +
> +static inline int avr_cpu_mmu_index(CPUAVRState *env, bool ifetch)
> +{
> +    return ifetch ? MMU_CODE_IDX : MMU_DATA_IDX;
> +}
> +
> +void avr_cpu_tcg_init(void);
> +
> +void avr_cpu_list(void);
> +int cpu_avr_exec(CPUState *cpu);
> +int cpu_avr_signal_handler(int host_signum, void *pinfo, void *puc);
> +int avr_cpu_handle_mmu_fault(CPUState *cpu, vaddr address, int size,
> +                                int rw, int mmu_idx);
> +int avr_cpu_memory_rw_debug(CPUState *cs, vaddr address, uint8_t *buf,
> +                                int len, bool is_write);
> +
> +enum {
> +    TB_FLAGS_FULL_ACCESS = 1,
> +    TB_FLAGS_SKIP = 2,
> +};
> +
> +static inline void cpu_get_tb_cpu_state(CPUAVRState *env, target_ulong *pc,
> +                                target_ulong *cs_base, uint32_t *pflags)
> +{
> +    uint32_t flags = 0;
> +
> +    *pc = env->pc_w * 2;
> +    *cs_base = 0;
> +
> +    if (env->fullacc) {
> +        flags |= TB_FLAGS_FULL_ACCESS;
> +    }
> +    if (env->skip) {
> +        flags |= TB_FLAGS_SKIP;
> +    }
> +
> +    *pflags = flags;
> +}
> +
> +static inline int cpu_interrupts_enabled(CPUAVRState *env)
> +{
> +    return env->sregI != 0;
> +}
> +
> +static inline uint8_t cpu_get_sreg(CPUAVRState *env)
> +{
> +    uint8_t sreg;
> +    sreg = (env->sregC) << 0
> +         | (env->sregZ) << 1
> +         | (env->sregN) << 2
> +         | (env->sregV) << 3
> +         | (env->sregS) << 4
> +         | (env->sregH) << 5
> +         | (env->sregT) << 6
> +         | (env->sregI) << 7;
> +    return sreg;
> +}
> +
> +static inline void cpu_set_sreg(CPUAVRState *env, uint8_t sreg)
> +{
> +    env->sregC = (sreg >> 0) & 0x01;
> +    env->sregZ = (sreg >> 1) & 0x01;
> +    env->sregN = (sreg >> 2) & 0x01;
> +    env->sregV = (sreg >> 3) & 0x01;
> +    env->sregS = (sreg >> 4) & 0x01;
> +    env->sregH = (sreg >> 5) & 0x01;
> +    env->sregT = (sreg >> 6) & 0x01;
> +    env->sregI = (sreg >> 7) & 0x01;
> +}
> +
> +bool avr_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
> +                        MMUAccessType access_type, int mmu_idx,
> +                        bool probe, uintptr_t retaddr);
> +
> +typedef CPUAVRState CPUArchState;
> +typedef AVRCPU ArchCPU;
> +
> +#include "exec/cpu-all.h"
> +
> +#endif /* !defined (QEMU_AVR_CPU_H) */
> diff --git a/target/avr/cpu.c b/target/avr/cpu.c
> new file mode 100644
> index 0000000000..dae56d7845
> --- /dev/null
> +++ b/target/avr/cpu.c
> @@ -0,0 +1,576 @@
> +/*
> + * QEMU AVR CPU
> + *
> + * Copyright (c) 2019 Michael Rolnik
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> + * <http://www.gnu.org/licenses/lgpl-2.1.html>
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qemu/qemu-print.h"
> +#include "exec/exec-all.h"
> +#include "cpu.h"
> +
> +static void avr_cpu_set_pc(CPUState *cs, vaddr value)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +
> +    cpu->env.pc_w = value / 2; /* internally PC points to words */
> +}
> +
> +static bool avr_cpu_has_work(CPUState *cs)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +    CPUAVRState *env = &cpu->env;
> +
> +    return (cs->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_RESET))
> +            && cpu_interrupts_enabled(env);
> +}
> +
> +static void avr_cpu_synchronize_from_tb(CPUState *cs, TranslationBlock *tb)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +    CPUAVRState *env = &cpu->env;
> +
> +    env->pc_w = tb->pc / 2; /* internally PC points to words */
> +}
> +
> +static void avr_cpu_reset(CPUState *cs)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +    AVRCPUClass *mcc = AVR_CPU_GET_CLASS(cpu);
> +    CPUAVRState *env = &cpu->env;
> +
> +    mcc->parent_reset(cs);
> +
> +    env->pc_w = 0;
> +    env->sregI = 1;
> +    env->sregC = 0;
> +    env->sregZ = 0;
> +    env->sregN = 0;
> +    env->sregV = 0;
> +    env->sregS = 0;
> +    env->sregH = 0;
> +    env->sregT = 0;
> +
> +    env->rampD = 0;
> +    env->rampX = 0;
> +    env->rampY = 0;
> +    env->rampZ = 0;
> +    env->eind = 0;
> +    env->sp = 0;
> +
> +    env->skip = 0;
> +
> +    memset(env->r, 0, sizeof(env->r));
> +
> +    tlb_flush(cs);
> +}
> +
> +static void avr_cpu_disas_set_info(CPUState *cpu, disassemble_info *info)
> +{
> +    info->mach = bfd_arch_avr;
> +    info->print_insn = NULL;
> +}
> +
> +static void avr_cpu_realizefn(DeviceState *dev, Error **errp)
> +{
> +    CPUState *cs = CPU(dev);
> +    AVRCPUClass *mcc = AVR_CPU_GET_CLASS(dev);
> +    Error *local_err = NULL;
> +
> +    cpu_exec_realizefn(cs, &local_err);
> +    if (local_err != NULL) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +    qemu_init_vcpu(cs);
> +    cpu_reset(cs);
> +
> +    mcc->parent_realize(dev, errp);
> +}
> +
> +static void avr_cpu_set_int(void *opaque, int irq, int level)
> +{
> +    AVRCPU *cpu = opaque;
> +    CPUAVRState *env = &cpu->env;
> +    CPUState *cs = CPU(cpu);
> +
> +    uint64_t mask = (1ull << irq);
> +    if (level) {
> +        env->intsrc |= mask;
> +        cpu_interrupt(cs, CPU_INTERRUPT_HARD);
> +    } else {
> +        env->intsrc &= ~mask;
> +        if (env->intsrc == 0) {
> +            cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
> +        }
> +    }
> +}
> +
> +static void avr_cpu_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +
> +    cpu_set_cpustate_pointers(cpu);
> +
> +#ifndef CONFIG_USER_ONLY
> +    /* Set the number of interrupts supported by the CPU. */
> +    qdev_init_gpio_in(DEVICE(cpu), avr_cpu_set_int, 57);
> +#endif
> +}
> +
> +static ObjectClass *avr_cpu_class_by_name(const char *cpu_model)
> +{
> +    ObjectClass *oc;
> +
> +    oc = object_class_by_name(cpu_model);
> +    if (object_class_dynamic_cast(oc, TYPE_AVR_CPU) == NULL ||
> +        object_class_is_abstract(oc)) {
> +        oc = NULL;
> +    }
> +    return oc;
> +}
> +
> +static void avr_cpu_dump_state(CPUState *cs, FILE *f, int flags)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +    CPUAVRState *env = &cpu->env;
> +    int i;
> +
> +    qemu_fprintf(f, "\n");
> +    qemu_fprintf(f, "PC:    %06x\n", env->pc_w);
> +    qemu_fprintf(f, "SP:      %04x\n", env->sp);
> +    qemu_fprintf(f, "rampD:     %02x\n", env->rampD >> 16);
> +    qemu_fprintf(f, "rampX:     %02x\n", env->rampX >> 16);
> +    qemu_fprintf(f, "rampY:     %02x\n", env->rampY >> 16);
> +    qemu_fprintf(f, "rampZ:     %02x\n", env->rampZ >> 16);
> +    qemu_fprintf(f, "EIND:      %02x\n", env->eind >> 16);
> +    qemu_fprintf(f, "X:       %02x%02x\n", env->r[27], env->r[26]);
> +    qemu_fprintf(f, "Y:       %02x%02x\n", env->r[29], env->r[28]);
> +    qemu_fprintf(f, "Z:       %02x%02x\n", env->r[31], env->r[30]);
> +    qemu_fprintf(f, "SREG:    [ %c %c %c %c %c %c %c %c ]\n",
> +                        env->sregI ? 'I' : '-',
> +                        env->sregT ? 'T' : '-',
> +                        env->sregH ? 'H' : '-',
> +                        env->sregS ? 'S' : '-',
> +                        env->sregV ? 'V' : '-',
> +                        env->sregN ? '-' : 'N', /* Zf has negative logic */
> +                        env->sregZ ? 'Z' : '-',
> +                        env->sregC ? 'I' : '-');
> +    qemu_fprintf(f, "SKIP:    %02x\n", env->skip);
> +
> +    qemu_fprintf(f, "\n");
> +    for (i = 0; i < ARRAY_SIZE(env->r); i++) {
> +        qemu_fprintf(f, "R[%02d]:  %02x   ", i, env->r[i]);
> +
> +        if ((i % 8) == 7) {
> +            qemu_fprintf(f, "\n");
> +        }
> +    }
> +    qemu_fprintf(f, "\n");
> +}
> +
> +static void avr_cpu_class_init(ObjectClass *oc, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +    CPUClass *cc = CPU_CLASS(oc);
> +    AVRCPUClass *mcc = AVR_CPU_CLASS(oc);
> +
> +    mcc->parent_realize = dc->realize;
> +    dc->realize = avr_cpu_realizefn;
> +
> +    mcc->parent_reset = cc->reset;
> +    cc->reset = avr_cpu_reset;
> +
> +    cc->class_by_name = avr_cpu_class_by_name;
> +
> +    cc->has_work = avr_cpu_has_work;
> +    cc->do_interrupt = avr_cpu_do_interrupt;
> +    cc->cpu_exec_interrupt = avr_cpu_exec_interrupt;
> +    cc->dump_state = avr_cpu_dump_state;
> +    cc->set_pc = avr_cpu_set_pc;
> +#if !defined(CONFIG_USER_ONLY)
> +    cc->memory_rw_debug = avr_cpu_memory_rw_debug;
> +#endif
> +#ifdef CONFIG_USER_ONLY
> +    cc->handle_mmu_fault = avr_cpu_handle_mmu_fault;
> +#else
> +    cc->get_phys_page_debug = avr_cpu_get_phys_page_debug;
> +    cc->vmsd = &vms_avr_cpu;
> +#endif
> +    cc->disas_set_info = avr_cpu_disas_set_info;
> +    cc->tlb_fill = avr_cpu_tlb_fill;
> +    cc->tcg_initialize = avr_cpu_tcg_init;
> +    cc->synchronize_from_tb = avr_cpu_synchronize_from_tb;
> +    cc->gdb_read_register = avr_cpu_gdb_read_register;
> +    cc->gdb_write_register = avr_cpu_gdb_write_register;
> +    cc->gdb_num_core_regs = 35;
> +    cc->gdb_core_xml_file = "avr-cpu.xml";
> +}
> +
> +static void avr_avr1_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +}
> +
> +static void avr_avr2_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +}
> +
> +static void avr_avr25_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +}
> +
> +static void avr_avr3_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +}
> +
> +static void avr_avr31_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +}
> +
> +static void avr_avr35_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +}
> +
> +static void avr_avr4_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +}
> +
> +static void avr_avr5_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +}
> +
> +static void avr_avr51_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_ELPMX);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +}
> +
> +static void avr_avr6_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_3_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_EIJMP_EICALL);
> +    avr_set_feature(env, AVR_FEATURE_ELPMX);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +}
> +
> +static void avr_xmega2_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +    avr_set_feature(env, AVR_FEATURE_RMW);
> +}
> +
> +static void avr_xmega4_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_ELPMX);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +    avr_set_feature(env, AVR_FEATURE_RMW);
> +}
> +
> +static void avr_xmega5_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPD);
> +    avr_set_feature(env, AVR_FEATURE_RAMPX);
> +    avr_set_feature(env, AVR_FEATURE_RAMPY);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_ELPMX);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +    avr_set_feature(env, AVR_FEATURE_RMW);
> +}
> +
> +static void avr_xmega6_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_3_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_EIJMP_EICALL);
> +    avr_set_feature(env, AVR_FEATURE_ELPMX);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +    avr_set_feature(env, AVR_FEATURE_RMW);
> +}
> +
> +static void avr_xmega7_initfn(Object *obj)
> +{
> +    AVRCPU *cpu = AVR_CPU(obj);
> +    CPUAVRState *env = &cpu->env;
> +
> +    avr_set_feature(env, AVR_FEATURE_LPM);
> +    avr_set_feature(env, AVR_FEATURE_IJMP_ICALL);
> +    avr_set_feature(env, AVR_FEATURE_ADIW_SBIW);
> +    avr_set_feature(env, AVR_FEATURE_SRAM);
> +    avr_set_feature(env, AVR_FEATURE_BREAK);
> +
> +    avr_set_feature(env, AVR_FEATURE_3_BYTE_PC);
> +    avr_set_feature(env, AVR_FEATURE_2_BYTE_SP);
> +    avr_set_feature(env, AVR_FEATURE_RAMPD);
> +    avr_set_feature(env, AVR_FEATURE_RAMPX);
> +    avr_set_feature(env, AVR_FEATURE_RAMPY);
> +    avr_set_feature(env, AVR_FEATURE_RAMPZ);
> +    avr_set_feature(env, AVR_FEATURE_EIJMP_EICALL);
> +    avr_set_feature(env, AVR_FEATURE_ELPMX);
> +    avr_set_feature(env, AVR_FEATURE_ELPM);
> +    avr_set_feature(env, AVR_FEATURE_JMP_CALL);
> +    avr_set_feature(env, AVR_FEATURE_LPMX);
> +    avr_set_feature(env, AVR_FEATURE_MOVW);
> +    avr_set_feature(env, AVR_FEATURE_MUL);
> +    avr_set_feature(env, AVR_FEATURE_RMW);
> +}
> +
> +typedef struct AVRCPUInfo {
> +    const char *name;
> +    void (*initfn)(Object *obj);
> +} AVRCPUInfo;
> +
> +
> +static void avr_cpu_list_entry(gpointer data, gpointer user_data)
> +{
> +    const char *typename = object_class_get_name(OBJECT_CLASS(data));
> +
> +    qemu_printf("%s\n", typename);
> +}
> +
> +void avr_cpu_list(void)
> +{
> +    GSList *list;
> +    list = object_class_get_list_sorted(TYPE_AVR_CPU, false);
> +    g_slist_foreach(list, avr_cpu_list_entry, NULL);
> +    g_slist_free(list);
> +}
> +
> +#define DEFINE_AVR_CPU_TYPE(model, initfn) \
> +    { \
> +        .parent = TYPE_AVR_CPU, \
> +        .instance_init = initfn, \
> +        .name = model "-avr-cpu", \
> +    }
> +
> +static const TypeInfo avr_cpu_type_info[] = {
> +    {
> +        .name = TYPE_AVR_CPU,
> +        .parent = TYPE_CPU,
> +        .instance_size = sizeof(AVRCPU),
> +        .instance_init = avr_cpu_initfn,
> +        .class_size = sizeof(AVRCPUClass),
> +        .class_init = avr_cpu_class_init,
> +        .abstract = true,
> +    },
> +    DEFINE_AVR_CPU_TYPE("avr1", avr_avr1_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr2", avr_avr2_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr25", avr_avr25_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr3", avr_avr3_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr31", avr_avr31_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr35", avr_avr35_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr4", avr_avr4_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr5", avr_avr5_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr51", avr_avr51_initfn),
> +    DEFINE_AVR_CPU_TYPE("avr6", avr_avr6_initfn),
> +    DEFINE_AVR_CPU_TYPE("xmega2", avr_xmega2_initfn),
> +    DEFINE_AVR_CPU_TYPE("xmega4", avr_xmega4_initfn),
> +    DEFINE_AVR_CPU_TYPE("xmega5", avr_xmega5_initfn),
> +    DEFINE_AVR_CPU_TYPE("xmega6", avr_xmega6_initfn),
> +    DEFINE_AVR_CPU_TYPE("xmega7", avr_xmega7_initfn),
> +};
> +
> +DEFINE_TYPES(avr_cpu_type_info)
> diff --git a/target/avr/gdbstub.c b/target/avr/gdbstub.c
> new file mode 100644
> index 0000000000..20a5252482
> --- /dev/null
> +++ b/target/avr/gdbstub.c
> @@ -0,0 +1,85 @@
> +/*
> + * QEMU AVR CPU
> + *
> + * Copyright (c) 2019 Michael Rolnik
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> + * <http://www.gnu.org/licenses/lgpl-2.1.html>
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +#include "exec/gdbstub.h"
> +
> +int avr_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +    CPUAVRState *env = &cpu->env;
> +
> +    /*  R */
> +    if (n < 32) {
> +        return gdb_get_reg8(mem_buf, env->r[n]);
> +    }
> +
> +    /*  SREG */
> +    if (n == 32) {
> +        uint8_t sreg = cpu_get_sreg(env);
> +
> +        return gdb_get_reg8(mem_buf, sreg);
> +    }
> +
> +    /*  SP */
> +    if (n == 33) {
> +        return gdb_get_reg16(mem_buf, env->sp & 0x0000ffff);
> +    }
> +
> +    /*  PC */
> +    if (n == 34) {
> +        return gdb_get_reg32(mem_buf, env->pc_w * 2);
> +    }
> +
> +    return 0;
> +}
> +
> +int avr_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
> +{
> +    AVRCPU *cpu = AVR_CPU(cs);
> +    CPUAVRState *env = &cpu->env;
> +
> +    /*  R */
> +    if (n < 32) {
> +        env->r[n] = *mem_buf;
> +        return 1;
> +    }
> +
> +    /*  SREG */
> +    if (n == 32) {
> +        cpu_set_sreg(env, *mem_buf);
> +        return 1;
> +    }
> +
> +    /*  SP */
> +    if (n == 33) {
> +        env->sp = lduw_p(mem_buf);
> +        return 2;
> +    }
> +
> +    /*  PC */
> +    if (n == 34) {
> +        env->pc_w = ldl_p(mem_buf) / 2;
> +        return 4;
> +    }
> +
> +    return 0;
> +}
> diff --git a/target/avr/machine.c b/target/avr/machine.c
> new file mode 100644
> index 0000000000..f6dcda7adc
> --- /dev/null
> +++ b/target/avr/machine.c
> @@ -0,0 +1,121 @@
> +/*
> + * QEMU AVR CPU
> + *
> + * Copyright (c) 2019 Michael Rolnik
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see
> + * <http://www.gnu.org/licenses/lgpl-2.1.html>
> + */
> +
> +#include "qemu/osdep.h"
> +#include "cpu.h"
> +#include "migration/cpu.h"
> +
> +static int get_sreg(QEMUFile *f, void *opaque, size_t size,
> +    const VMStateField *field)
> +{
> +    CPUAVRState *env = opaque;
> +    uint8_t sreg;
> +
> +    sreg = qemu_get_byte(f);
> +    cpu_set_sreg(env, sreg);
> +    return 0;
> +}
> +
> +static int put_sreg(
> +    QEMUFile *f, void *opaque, size_t size,
> +    const VMStateField *field, QJSON *vmdesc)
> +{
> +    CPUAVRState *env = opaque;
> +    uint8_t sreg = cpu_get_sreg(env);
> +
> +    qemu_put_byte(f, sreg);
> +    return 0;
> +}
> +
> +static const VMStateInfo vms_sreg = {
> +    .name = "sreg",
> +    .get = get_sreg,
> +    .put = put_sreg,
> +};
> +
> +static int get_segment(
> +    QEMUFile *f, void *opaque, size_t size, const VMStateField *field)
> +{
> +    uint32_t *ramp = opaque;
> +    uint8_t temp;
> +
> +    temp = qemu_get_byte(f);
> +    *ramp = ((uint32_t)temp) << 16;
> +    return 0;
> +}
> +
> +static int put_segment(
> +    QEMUFile *f, void *opaque, size_t size,
> +    const VMStateField *field, QJSON *vmdesc)
> +{
> +    uint32_t *ramp = opaque;
> +    uint8_t temp = *ramp >> 16;
> +
> +    qemu_put_byte(f, temp);
> +    return 0;
> +}
> +
> +static const VMStateInfo vms_rampD = {
> +    .name = "rampD",
> +    .get = get_segment,
> +    .put = put_segment,
> +};
> +static const VMStateInfo vms_rampX = {
> +    .name = "rampX",
> +    .get = get_segment,
> +    .put = put_segment,
> +};
> +static const VMStateInfo vms_rampY = {
> +    .name = "rampY",
> +    .get = get_segment,
> +    .put = put_segment,
> +};
> +static const VMStateInfo vms_rampZ = {
> +    .name = "rampZ",
> +    .get = get_segment,
> +    .put = put_segment,
> +};
> +static const VMStateInfo vms_eind = {
> +    .name = "eind",
> +    .get = get_segment,
> +    .put = put_segment,
> +};
> +
> +const VMStateDescription vms_avr_cpu = {
> +    .name = "cpu",
> +    .version_id = 0,
> +    .minimum_version_id = 0,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT32(env.pc_w, AVRCPU),
> +        VMSTATE_UINT32(env.sp, AVRCPU),
> +        VMSTATE_UINT32(env.skip, AVRCPU),
> +
> +        VMSTATE_UINT32_ARRAY(env.r, AVRCPU, NO_CPU_REGISTERS),
> +
> +        VMSTATE_SINGLE(env, AVRCPU, 0, vms_sreg, CPUAVRState),
> +        VMSTATE_SINGLE(env.rampD, AVRCPU, 0, vms_rampD, uint32_t),
> +        VMSTATE_SINGLE(env.rampX, AVRCPU, 0, vms_rampX, uint32_t),
> +        VMSTATE_SINGLE(env.rampY, AVRCPU, 0, vms_rampY, uint32_t),
> +        VMSTATE_SINGLE(env.rampZ, AVRCPU, 0, vms_rampZ, uint32_t),
> +        VMSTATE_SINGLE(env.eind, AVRCPU, 0, vms_eind, uint32_t),
> +
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> diff --git a/gdb-xml/avr-cpu.xml b/gdb-xml/avr-cpu.xml
> new file mode 100644
> index 0000000000..c4747f5b40
> --- /dev/null
> +++ b/gdb-xml/avr-cpu.xml
> @@ -0,0 +1,49 @@
> +<?xml version="1.0"?>
> +<!-- Copyright (C) 2018-2019 Free Software Foundation, Inc.
> +
> +     Copying and distribution of this file, with or without modification,
> +     are permitted in any medium without royalty provided the copyright
> +     notice and this notice are preserved.  -->
> +
> +<!-- Register numbers are hard-coded in order to maintain backward
> +     compatibility with older versions of tools that didn't use xml
> +     register descriptions.  -->
> +
> +<!DOCTYPE feature SYSTEM "gdb-target.dtd">
> +<feature name="org.gnu.gdb.riscv.cpu">
> +  <reg name="r0" bitsize="8" type="int" regnum="0"/>
> +  <reg name="r1" bitsize="8" type="int"/>
> +  <reg name="r2" bitsize="8" type="int"/>
> +  <reg name="r3" bitsize="8" type="int"/>
> +  <reg name="r4" bitsize="8" type="int"/>
> +  <reg name="r5" bitsize="8" type="int"/>
> +  <reg name="r6" bitsize="8" type="int"/>
> +  <reg name="r7" bitsize="8" type="int"/>
> +  <reg name="r8" bitsize="8" type="int"/>
> +  <reg name="r9" bitsize="8" type="int"/>
> +  <reg name="r10" bitsize="8" type="int"/>
> +  <reg name="r11" bitsize="8" type="int"/>
> +  <reg name="r12" bitsize="8" type="int"/>
> +  <reg name="r13" bitsize="8" type="int"/>
> +  <reg name="r14" bitsize="8" type="int"/>
> +  <reg name="r15" bitsize="8" type="int"/>
> +  <reg name="r16" bitsize="8" type="int"/>
> +  <reg name="r17" bitsize="8" type="int"/>
> +  <reg name="r18" bitsize="8" type="int"/>
> +  <reg name="r19" bitsize="8" type="int"/>
> +  <reg name="r20" bitsize="8" type="int"/>
> +  <reg name="r21" bitsize="8" type="int"/>
> +  <reg name="r22" bitsize="8" type="int"/>
> +  <reg name="r23" bitsize="8" type="int"/>
> +  <reg name="r24" bitsize="8" type="int"/>
> +  <reg name="r25" bitsize="8" type="int"/>
> +  <reg name="r26" bitsize="8" type="int"/>
> +  <reg name="r27" bitsize="8" type="int"/>
> +  <reg name="r28" bitsize="8" type="int"/>
> +  <reg name="r29" bitsize="8" type="int"/>
> +  <reg name="r30" bitsize="8" type="int"/>
> +  <reg name="r31" bitsize="8" type="int"/>
> +  <reg name="sreg" bitsize="8" type="int"/>
> +  <reg name="sp" bitsize="8" type="int"/>
> +  <reg name="pc" bitsize="8" type="int"/>
> +</feature>
> -- 
> 2.17.2 (Apple Git-113)