diff --git a/gdbstub.c b/gdbstub.c
index db537a712c..0bcfc47a7c 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -319,8 +319,8 @@ static int gdb_signal_to_target (int sig)
 typedef struct GDBRegisterState {
     int base_reg;
     int num_regs;
-    gdb_reg_cb get_reg;
-    gdb_reg_cb set_reg;
+    gdb_get_reg_cb get_reg;
+    gdb_set_reg_cb set_reg;
     const char *xml;
     struct GDBRegisterState *next;
 } GDBRegisterState;
@@ -905,19 +905,19 @@ static const char *get_feature_xml(const char *p, const char **newp,
     return name ? xml_builtin[i][1] : NULL;
 }
 
-static int gdb_read_register(CPUState *cpu, uint8_t *mem_buf, int reg)
+static int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
     CPUArchState *env = cpu->env_ptr;
     GDBRegisterState *r;
 
     if (reg < cc->gdb_num_core_regs) {
-        return cc->gdb_read_register(cpu, mem_buf, reg);
+        return cc->gdb_read_register(cpu, buf, reg);
     }
 
     for (r = cpu->gdb_regs; r; r = r->next) {
         if (r->base_reg <= reg && reg < r->base_reg + r->num_regs) {
-            return r->get_reg(env, mem_buf, reg - r->base_reg);
+            return r->get_reg(env, buf, reg - r->base_reg);
         }
     }
     return 0;
@@ -948,7 +948,7 @@ static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
  */
 
 void gdb_register_coprocessor(CPUState *cpu,
-                              gdb_reg_cb get_reg, gdb_reg_cb set_reg,
+                              gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
                               int num_regs, const char *xml, int g_pos)
 {
     GDBRegisterState *s;
@@ -1739,7 +1739,7 @@ static void handle_get_reg(GdbCmdContext *gdb_ctx, void *user_ctx)
     }
 
     reg_size = gdb_read_register(gdbserver_state.g_cpu,
-                                 gdbserver_state.mem_buf->data,
+                                 gdbserver_state.mem_buf,
                                  gdb_ctx->params[0].val_ull);
     if (!reg_size) {
         put_packet("E14");
@@ -1832,14 +1832,14 @@ static void handle_read_all_regs(GdbCmdContext *gdb_ctx, void *user_ctx)
     target_ulong addr, len;
 
     cpu_synchronize_state(gdbserver_state.g_cpu);
+    g_byte_array_set_size(gdbserver_state.mem_buf, 0);
     len = 0;
     for (addr = 0; addr < gdbserver_state.g_cpu->gdb_num_g_regs; addr++) {
         len += gdb_read_register(gdbserver_state.g_cpu,
-                                 gdbserver_state.mem_buf->data + len,
+                                 gdbserver_state.mem_buf,
                                  addr);
     }
-    /* FIXME: This is after the fact sizing */
-    g_byte_array_set_size(gdbserver_state.mem_buf, len);
+    g_assert(len == gdbserver_state.mem_buf->len);
 
     memtohex(gdbserver_state.str_buf, gdbserver_state.mem_buf->data, len);
     put_strbuf();
diff --git a/hw/core/cpu.c b/hw/core/cpu.c
index fe65ca62ac..3b2363f043 100644
--- a/hw/core/cpu.c
+++ b/hw/core/cpu.c
@@ -177,7 +177,7 @@ static int cpu_common_write_elf64_note(WriteCoreDumpFunction f,
 }
 
 
-static int cpu_common_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg)
+static int cpu_common_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
 {
     return 0;
 }
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 59e366ba3a..30b909ebd2 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -68,53 +68,76 @@ void gdb_signalled(CPUArchState *, int);
 void gdbserver_fork(CPUState *);
 #endif
 /* Get or set a register.  Returns the size of the register.  */
-typedef int (*gdb_reg_cb)(CPUArchState *env, uint8_t *buf, int reg);
+typedef int (*gdb_get_reg_cb)(CPUArchState *env, GByteArray *buf, int reg);
+typedef int (*gdb_set_reg_cb)(CPUArchState *env, uint8_t *buf, int reg);
 void gdb_register_coprocessor(CPUState *cpu,
-                              gdb_reg_cb get_reg, gdb_reg_cb set_reg,
+                              gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
                               int num_regs, const char *xml, int g_pos);
 
-/* The GDB remote protocol transfers values in target byte order.  This means
- * we can use the raw memory access routines to access the value buffer.
- * Conveniently, these also handle the case where the buffer is mis-aligned.
+/*
+ * The GDB remote protocol transfers values in target byte order. As
+ * the gdbstub may be batching up several register values we always
+ * append to the array.
  */
 
-static inline int gdb_get_reg8(uint8_t *mem_buf, uint8_t val)
+static inline int gdb_get_reg8(GByteArray *buf, uint8_t val)
 {
-    stb_p(mem_buf, val);
+    g_byte_array_append(buf, &val, 1);
     return 1;
 }
 
-static inline int gdb_get_reg16(uint8_t *mem_buf, uint16_t val)
+static inline int gdb_get_reg16(GByteArray *buf, uint16_t val)
 {
-    stw_p(mem_buf, val);
+    uint16_t to_word = tswap16(val);
+    g_byte_array_append(buf, (uint8_t *) &to_word, 2);
     return 2;
 }
 
-static inline int gdb_get_reg32(uint8_t *mem_buf, uint32_t val)
+static inline int gdb_get_reg32(GByteArray *buf, uint32_t val)
 {
-    stl_p(mem_buf, val);
+    uint32_t to_long = tswap32(val);
+    g_byte_array_append(buf, (uint8_t *) &to_long, 4);
     return 4;
 }
 
-static inline int gdb_get_reg64(uint8_t *mem_buf, uint64_t val)
+static inline int gdb_get_reg64(GByteArray *buf, uint64_t val)
 {
-    stq_p(mem_buf, val);
+    uint64_t to_quad = tswap64(val);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
     return 8;
 }
 
-static inline int gdb_get_reg128(uint8_t *mem_buf, uint64_t val_hi,
+static inline int gdb_get_reg128(GByteArray *buf, uint64_t val_hi,
                                  uint64_t val_lo)
 {
+    uint64_t to_quad;
 #ifdef TARGET_WORDS_BIGENDIAN
-    stq_p(mem_buf, val_hi);
-    stq_p(mem_buf + 8, val_lo);
+    to_quad = tswap64(val_hi);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
+    to_quad = tswap64(val_lo);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
 #else
-    stq_p(mem_buf, val_lo);
-    stq_p(mem_buf + 8, val_hi);
+    to_quad = tswap64(val_lo);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
+    to_quad = tswap64(val_hi);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
 #endif
     return 16;
 }
 
+/**
+ * gdb_get_reg_ptr: get pointer to start of last element
+ * @len: length of element
+ *
+ * This is a helper function to extract the pointer to the last
+ * element for additional processing. Some front-ends do additional
+ * dynamic swapping of the elements based on CPU state.
+ */
+static inline uint8_t * gdb_get_reg_ptr(GByteArray *buf, int len)
+{
+    return buf->data + buf->len - len;
+}
+
 #if TARGET_LONG_BITS == 64
 #define gdb_get_regl(buf, val) gdb_get_reg64(buf, val)
 #define ldtul_p(addr) ldq_p(addr)
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 73e9a869a4..e1d6ee00b4 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -195,7 +195,7 @@ typedef struct CPUClass {
     hwaddr (*get_phys_page_attrs_debug)(CPUState *cpu, vaddr addr,
                                         MemTxAttrs *attrs);
     int (*asidx_from_attrs)(CPUState *cpu, MemTxAttrs attrs);
-    int (*gdb_read_register)(CPUState *cpu, uint8_t *buf, int reg);
+    int (*gdb_read_register)(CPUState *cpu, GByteArray *buf, int reg);
     int (*gdb_write_register)(CPUState *cpu, uint8_t *buf, int reg);
     bool (*debug_check_watchpoint)(CPUState *cpu, CPUWatchpoint *wp);
     void (*debug_excp_handler)(CPUState *cpu);
diff --git a/target/alpha/cpu.h b/target/alpha/cpu.h
index 3f782c0efe..be29bdd530 100644
--- a/target/alpha/cpu.h
+++ b/target/alpha/cpu.h
@@ -280,7 +280,7 @@ void alpha_cpu_do_interrupt(CPUState *cpu);
 bool alpha_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void alpha_cpu_dump_state(CPUState *cs, FILE *f, int flags);
 hwaddr alpha_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int alpha_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int alpha_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int alpha_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void alpha_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
                                    MMUAccessType access_type,
diff --git a/target/alpha/gdbstub.c b/target/alpha/gdbstub.c
index 7f9cc092a9..0cd76ddaa9 100644
--- a/target/alpha/gdbstub.c
+++ b/target/alpha/gdbstub.c
@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int alpha_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int alpha_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     AlphaCPU *cpu = ALPHA_CPU(cs);
     CPUAlphaState *env = &cpu->env;
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 4ffd991b6f..4ab2cbfd41 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -968,7 +968,7 @@ bool arm_cpu_exec_interrupt(CPUState *cpu, int int_req);
 hwaddr arm_cpu_get_phys_page_attrs_debug(CPUState *cpu, vaddr addr,
                                          MemTxAttrs *attrs);
 
-int arm_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int arm_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int arm_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 /* Dynamically generates for gdb stub an XML description of the sysregs from
@@ -988,7 +988,7 @@ int arm_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
                              int cpuid, void *opaque);
 
 #ifdef TARGET_AARCH64
-int aarch64_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int aarch64_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int aarch64_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void aarch64_sve_narrow_vq(CPUARMState *env, unsigned vq);
 void aarch64_sve_change_el(CPUARMState *env, int old_el,
diff --git a/target/arm/gdbstub.c b/target/arm/gdbstub.c
index 1239abd984..4557775d24 100644
--- a/target/arm/gdbstub.c
+++ b/target/arm/gdbstub.c
@@ -32,7 +32,7 @@ typedef struct RegisterSysregXmlParam {
    We hack round this by giving the FPA regs zero size when talking to a
    newer gdb.  */
 
-int arm_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int arm_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
diff --git a/target/arm/gdbstub64.c b/target/arm/gdbstub64.c
index 665ebb3ef6..35d0b80c2d 100644
--- a/target/arm/gdbstub64.c
+++ b/target/arm/gdbstub64.c
@@ -20,7 +20,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int aarch64_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int aarch64_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 69104fb351..c0e1ba1727 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -48,30 +48,27 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
 
 static void switch_mode(CPUARMState *env, int mode);
 
-static int vfp_gdb_get_reg(CPUARMState *env, uint8_t *buf, int reg)
+static int vfp_gdb_get_reg(CPUARMState *env, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = env_archcpu(env);
     int nregs = cpu_isar_feature(aa32_simd_r32, cpu) ? 32 : 16;
 
     /* VFP data registers are always little-endian.  */
     if (reg < nregs) {
-        stq_le_p(buf, *aa32_vfp_dreg(env, reg));
-        return 8;
+        return gdb_get_reg64(buf, *aa32_vfp_dreg(env, reg));
     }
     if (arm_feature(env, ARM_FEATURE_NEON)) {
         /* Aliases for Q regs.  */
         nregs += 16;
         if (reg < nregs) {
             uint64_t *q = aa32_vfp_qreg(env, reg - 32);
-            stq_le_p(buf, q[0]);
-            stq_le_p(buf + 8, q[1]);
-            return 16;
+            return gdb_get_reg128(buf, q[0], q[1]);
         }
     }
     switch (reg - nregs) {
-    case 0: stl_p(buf, env->vfp.xregs[ARM_VFP_FPSID]); return 4;
-    case 1: stl_p(buf, vfp_get_fpscr(env)); return 4;
-    case 2: stl_p(buf, env->vfp.xregs[ARM_VFP_FPEXC]); return 4;
+    case 0: return gdb_get_reg32(buf, env->vfp.xregs[ARM_VFP_FPSID]); break;
+    case 1: return gdb_get_reg32(buf, vfp_get_fpscr(env)); break;
+    case 2: return gdb_get_reg32(buf, env->vfp.xregs[ARM_VFP_FPEXC]); break;
     }
     return 0;
 }
@@ -102,7 +99,7 @@ static int vfp_gdb_set_reg(CPUARMState *env, uint8_t *buf, int reg)
     return 0;
 }
 
-static int aarch64_fpu_gdb_get_reg(CPUARMState *env, uint8_t *buf, int reg)
+static int aarch64_fpu_gdb_get_reg(CPUARMState *env, GByteArray *buf, int reg)
 {
     switch (reg) {
     case 0 ... 31:
@@ -205,7 +202,7 @@ static void write_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri,
     }
 }
 
-static int arm_gdb_get_sysreg(CPUARMState *env, uint8_t *buf, int reg)
+static int arm_gdb_get_sysreg(CPUARMState *env, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = env_archcpu(env);
     const ARMCPRegInfo *ri;
diff --git a/target/cris/cpu.h b/target/cris/cpu.h
index ca240bc788..8f08d7628b 100644
--- a/target/cris/cpu.h
+++ b/target/cris/cpu.h
@@ -195,8 +195,8 @@ void cris_cpu_dump_state(CPUState *cs, FILE *f, int flags);
 
 hwaddr cris_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
 
-int crisv10_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
-int cris_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int crisv10_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
+int cris_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int cris_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 /* you can call this signal handler from your SIGBUS and SIGSEGV
diff --git a/target/cris/gdbstub.c b/target/cris/gdbstub.c
index a3d76d2e8c..b01b2aa081 100644
--- a/target/cris/gdbstub.c
+++ b/target/cris/gdbstub.c
@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int crisv10_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int crisv10_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     CRISCPU *cpu = CRIS_CPU(cs);
     CPUCRISState *env = &cpu->env;
@@ -53,7 +53,7 @@ int crisv10_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
     return 0;
 }
 
-int cris_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int cris_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     CRISCPU *cpu = CRIS_CPU(cs);
     CPUCRISState *env = &cpu->env;
diff --git a/target/hppa/cpu.h b/target/hppa/cpu.h
index 6713d04f11..801a4fb1ba 100644
--- a/target/hppa/cpu.h
+++ b/target/hppa/cpu.h
@@ -321,7 +321,7 @@ void cpu_hppa_change_prot_id(CPUHPPAState *env);
 
 int cpu_hppa_signal_handler(int host_signum, void *pinfo, void *puc);
 hwaddr hppa_cpu_get_phys_page_debug(CPUState *cs, vaddr addr);
-int hppa_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int hppa_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int hppa_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void hppa_cpu_do_interrupt(CPUState *cpu);
 bool hppa_cpu_exec_interrupt(CPUState *cpu, int int_req);
diff --git a/target/hppa/gdbstub.c b/target/hppa/gdbstub.c
index 341888a9da..a6428a2893 100644
--- a/target/hppa/gdbstub.c
+++ b/target/hppa/gdbstub.c
@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int hppa_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int hppa_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     HPPACPU *cpu = HPPA_CPU(cs);
     CPUHPPAState *env = &cpu->env;
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 576f309bbf..c2d89315b9 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1766,7 +1766,7 @@ void x86_cpu_dump_state(CPUState *cs, FILE *f, int flags);
 hwaddr x86_cpu_get_phys_page_attrs_debug(CPUState *cpu, vaddr addr,
                                          MemTxAttrs *attrs);
 
-int x86_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int x86_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int x86_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 void x86_cpu_exec_enter(CPUState *cpu);
diff --git a/target/i386/gdbstub.c b/target/i386/gdbstub.c
index e4d8cb66c0..f3d23b614e 100644
--- a/target/i386/gdbstub.c
+++ b/target/i386/gdbstub.c
@@ -79,7 +79,7 @@ static const int gpr_map32[8] = { 0, 1, 2, 3, 4, 5, 6, 7 };
 #endif
 
 
-int x86_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int x86_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     X86CPU *cpu = X86_CPU(cs);
     CPUX86State *env = &cpu->env;
diff --git a/target/lm32/cpu.h b/target/lm32/cpu.h
index 064c6b1267..01d408eb55 100644
--- a/target/lm32/cpu.h
+++ b/target/lm32/cpu.h
@@ -202,7 +202,7 @@ void lm32_cpu_do_interrupt(CPUState *cpu);
 bool lm32_cpu_exec_interrupt(CPUState *cs, int int_req);
 void lm32_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr lm32_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int lm32_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int lm32_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int lm32_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 typedef enum {
diff --git a/target/lm32/gdbstub.c b/target/lm32/gdbstub.c
index 82ede436e1..b6fe12e1d6 100644
--- a/target/lm32/gdbstub.c
+++ b/target/lm32/gdbstub.c
@@ -22,7 +22,7 @@
 #include "exec/gdbstub.h"
 #include "hw/lm32/lm32_pic.h"
 
-int lm32_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int lm32_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     LM32CPU *cpu = LM32_CPU(cs);
     CPULM32State *env = &cpu->env;
diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 3de8e06dfe..521ac67cdd 100644
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -168,7 +168,7 @@ void m68k_cpu_do_interrupt(CPUState *cpu);
 bool m68k_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void m68k_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr m68k_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int m68k_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int m68k_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int m68k_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 void m68k_tcg_init(void);
diff --git a/target/m68k/gdbstub.c b/target/m68k/gdbstub.c
index fdc96f57ff..eb2d030e14 100644
--- a/target/m68k/gdbstub.c
+++ b/target/m68k/gdbstub.c
@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int m68k_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int m68k_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     M68kCPU *cpu = M68K_CPU(cs);
     CPUM68KState *env = &cpu->env;
diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index c23b70f854..014657c637 100644
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -68,7 +68,7 @@ void m68k_cpu_list(void)
     g_slist_free(list);
 }
 
-static int cf_fpu_gdb_get_reg(CPUM68KState *env, uint8_t *mem_buf, int n)
+static int cf_fpu_gdb_get_reg(CPUM68KState *env, GByteArray *mem_buf, int n)
 {
     if (n < 8) {
         float_status s;
@@ -105,7 +105,7 @@ static int cf_fpu_gdb_set_reg(CPUM68KState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int m68k_fpu_gdb_get_reg(CPUM68KState *env, uint8_t *mem_buf, int n)
+static int m68k_fpu_gdb_get_reg(CPUM68KState *env, GByteArray *mem_buf, int n)
 {
     if (n < 8) {
         int len = gdb_get_reg16(mem_buf, env->fregs[n].l.upper);
diff --git a/target/microblaze/cpu.h b/target/microblaze/cpu.h
index 32522f606b..1a700a880c 100644
--- a/target/microblaze/cpu.h
+++ b/target/microblaze/cpu.h
@@ -313,7 +313,7 @@ void mb_cpu_do_interrupt(CPUState *cs);
 bool mb_cpu_exec_interrupt(CPUState *cs, int int_req);
 void mb_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr mb_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int mb_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int mb_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int mb_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 void mb_tcg_init(void);
diff --git a/target/microblaze/gdbstub.c b/target/microblaze/gdbstub.c
index 30677b6d1f..f41ebf1f33 100644
--- a/target/microblaze/gdbstub.c
+++ b/target/microblaze/gdbstub.c
@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int mb_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int mb_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     MicroBlazeCPU *cpu = MICROBLAZE_CPU(cs);
     CPUMBState *env = &cpu->env;
diff --git a/target/mips/gdbstub.c b/target/mips/gdbstub.c
index bbb2544939..98f56e660d 100644
--- a/target/mips/gdbstub.c
+++ b/target/mips/gdbstub.c
@@ -22,7 +22,7 @@
 #include "internal.h"
 #include "exec/gdbstub.h"
 
-int mips_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int mips_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     MIPSCPU *cpu = MIPS_CPU(cs);
     CPUMIPSState *env = &cpu->env;
diff --git a/target/mips/internal.h b/target/mips/internal.h
index df55f845ba..1bf274b3ef 100644
--- a/target/mips/internal.h
+++ b/target/mips/internal.h
@@ -82,7 +82,7 @@ void mips_cpu_do_interrupt(CPUState *cpu);
 bool mips_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void mips_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr mips_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int mips_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int mips_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int mips_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void mips_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
                                   MMUAccessType access_type,
diff --git a/target/nios2/cpu.c b/target/nios2/cpu.c
index 1c0c855a6f..1856b7fcc7 100644
--- a/target/nios2/cpu.c
+++ b/target/nios2/cpu.c
@@ -124,7 +124,7 @@ static void nios2_cpu_disas_set_info(CPUState *cpu, disassemble_info *info)
 #endif
 }
 
-static int nios2_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+static int nios2_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);
     CPUClass *cc = CPU_GET_CLASS(cs);
diff --git a/target/openrisc/cpu.h b/target/openrisc/cpu.h
index 0ad02eab79..d9484b802f 100644
--- a/target/openrisc/cpu.h
+++ b/target/openrisc/cpu.h
@@ -320,7 +320,7 @@ void openrisc_cpu_do_interrupt(CPUState *cpu);
 bool openrisc_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void openrisc_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr openrisc_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int openrisc_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int openrisc_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int openrisc_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void openrisc_translate_init(void);
 bool openrisc_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
diff --git a/target/openrisc/gdbstub.c b/target/openrisc/gdbstub.c
index 0fcdb79668..095bf76c12 100644
--- a/target/openrisc/gdbstub.c
+++ b/target/openrisc/gdbstub.c
@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int openrisc_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int openrisc_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     OpenRISCCPU *cpu = OPENRISC_CPU(cs);
     CPUOpenRISCState *env = &cpu->env;
diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index b283042515..5fd081573e 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1218,8 +1218,8 @@ bool ppc_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void ppc_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 void ppc_cpu_dump_statistics(CPUState *cpu, int flags);
 hwaddr ppc_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int ppc_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
-int ppc_cpu_gdb_read_register_apple(CPUState *cpu, uint8_t *buf, int reg);
+int ppc_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
+int ppc_cpu_gdb_read_register_apple(CPUState *cpu, GByteArray *buf, int reg);
 int ppc_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 int ppc_cpu_gdb_write_register_apple(CPUState *cpu, uint8_t *buf, int reg);
 #ifndef CONFIG_USER_ONLY
diff --git a/target/ppc/gdbstub.c b/target/ppc/gdbstub.c
index 823759c92e..eb362dd9ae 100644
--- a/target/ppc/gdbstub.c
+++ b/target/ppc/gdbstub.c
@@ -114,10 +114,11 @@ void ppc_maybe_bswap_register(CPUPPCState *env, uint8_t *mem_buf, int len)
  * the FP regs zero size when talking to a newer gdb.
  */
 
-int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int ppc_cpu_gdb_read_register(CPUState *cs, GByteArray *buf, int n)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
     CPUPPCState *env = &cpu->env;
+    uint8_t *mem_buf;
     int r = ppc_gdb_register_len(n);
 
     if (!r) {
@@ -126,17 +127,17 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
 
     if (n < 32) {
         /* gprs */
-        gdb_get_regl(mem_buf, env->gpr[n]);
+        gdb_get_regl(buf, env->gpr[n]);
     } else if (n < 64) {
         /* fprs */
-        stfq_p(mem_buf, *cpu_fpr_ptr(env, n - 32));
+        gdb_get_reg64(buf, *cpu_fpr_ptr(env, n - 32));
     } else {
         switch (n) {
         case 64:
-            gdb_get_regl(mem_buf, env->nip);
+            gdb_get_regl(buf, env->nip);
             break;
         case 65:
-            gdb_get_regl(mem_buf, env->msr);
+            gdb_get_regl(buf, env->msr);
             break;
         case 66:
             {
@@ -145,31 +146,33 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
                 for (i = 0; i < 8; i++) {
                     cr |= env->crf[i] << (32 - ((i + 1) * 4));
                 }
-                gdb_get_reg32(mem_buf, cr);
+                gdb_get_reg32(buf, cr);
                 break;
             }
         case 67:
-            gdb_get_regl(mem_buf, env->lr);
+            gdb_get_regl(buf, env->lr);
             break;
         case 68:
-            gdb_get_regl(mem_buf, env->ctr);
+            gdb_get_regl(buf, env->ctr);
             break;
         case 69:
-            gdb_get_reg32(mem_buf, env->xer);
+            gdb_get_reg32(buf, env->xer);
             break;
         case 70:
-            gdb_get_reg32(mem_buf, env->fpscr);
+            gdb_get_reg32(buf, env->fpscr);
             break;
         }
     }
+    mem_buf = buf->data + buf->len - r;
     ppc_maybe_bswap_register(env, mem_buf, r);
     return r;
 }
 
-int ppc_cpu_gdb_read_register_apple(CPUState *cs, uint8_t *mem_buf, int n)
+int ppc_cpu_gdb_read_register_apple(CPUState *cs, GByteArray *buf, int n)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
     CPUPPCState *env = &cpu->env;
+    uint8_t *mem_buf;
     int r = ppc_gdb_register_len_apple(n);
 
     if (!r) {
@@ -178,21 +181,21 @@ int ppc_cpu_gdb_read_register_apple(CPUState *cs, uint8_t *mem_buf, int n)
 
     if (n < 32) {
         /* gprs */
-        gdb_get_reg64(mem_buf, env->gpr[n]);
+        gdb_get_reg64(buf, env->gpr[n]);
     } else if (n < 64) {
         /* fprs */
-        stfq_p(mem_buf, *cpu_fpr_ptr(env, n - 32));
+        gdb_get_reg64(buf, *cpu_fpr_ptr(env, n - 32));
     } else if (n < 96) {
         /* Altivec */
-        stq_p(mem_buf, n - 64);
-        stq_p(mem_buf + 8, 0);
+        gdb_get_reg64(buf, n - 64);
+        gdb_get_reg64(buf, 0);
     } else {
         switch (n) {
         case 64 + 32:
-            gdb_get_reg64(mem_buf, env->nip);
+            gdb_get_reg64(buf, env->nip);
             break;
         case 65 + 32:
-            gdb_get_reg64(mem_buf, env->msr);
+            gdb_get_reg64(buf, env->msr);
             break;
         case 66 + 32:
             {
@@ -201,23 +204,24 @@ int ppc_cpu_gdb_read_register_apple(CPUState *cs, uint8_t *mem_buf, int n)
                 for (i = 0; i < 8; i++) {
                     cr |= env->crf[i] << (32 - ((i + 1) * 4));
                 }
-                gdb_get_reg32(mem_buf, cr);
+                gdb_get_reg32(buf, cr);
                 break;
             }
         case 67 + 32:
-            gdb_get_reg64(mem_buf, env->lr);
+            gdb_get_reg64(buf, env->lr);
             break;
         case 68 + 32:
-            gdb_get_reg64(mem_buf, env->ctr);
+            gdb_get_reg64(buf, env->ctr);
             break;
         case 69 + 32:
-            gdb_get_reg32(mem_buf, env->xer);
+            gdb_get_reg32(buf, env->xer);
             break;
         case 70 + 32:
-            gdb_get_reg64(mem_buf, env->fpscr);
+            gdb_get_reg64(buf, env->fpscr);
             break;
         }
     }
+    mem_buf = buf->data + buf->len - r;
     ppc_maybe_bswap_register(env, mem_buf, r);
     return r;
 }
diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
index 53995f62ea..04ad54cff6 100644
--- a/target/ppc/translate_init.inc.c
+++ b/target/ppc/translate_init.inc.c
@@ -9857,7 +9857,7 @@ static int gdb_find_spr_idx(CPUPPCState *env, int n)
     return -1;
 }
 
-static int gdb_get_spr_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
+static int gdb_get_spr_reg(CPUPPCState *env, GByteArray *buf, int n)
 {
     int reg;
     int len;
@@ -9868,8 +9868,8 @@ static int gdb_get_spr_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
     }
 
     len = TARGET_LONG_SIZE;
-    stn_p(mem_buf, len, env->spr[reg]);
-    ppc_maybe_bswap_register(env, mem_buf, len);
+    gdb_get_regl(buf, env->spr[reg]);
+    ppc_maybe_bswap_register(env, gdb_get_reg_ptr(buf, len), len);
     return len;
 }
 
@@ -9891,15 +9891,18 @@ static int gdb_set_spr_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
 }
 #endif
 
-static int gdb_get_float_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
+static int gdb_get_float_reg(CPUPPCState *env, GByteArray *buf, int n)
 {
+    uint8_t *mem_buf;
     if (n < 32) {
-        stfq_p(mem_buf, *cpu_fpr_ptr(env, n));
+        gdb_get_reg64(buf, *cpu_fpr_ptr(env, n));
+        mem_buf = gdb_get_reg_ptr(buf, 8);
         ppc_maybe_bswap_register(env, mem_buf, 8);
         return 8;
     }
     if (n == 32) {
-        stl_p(mem_buf, env->fpscr);
+        gdb_get_reg32(buf, env->fpscr);
+        mem_buf = gdb_get_reg_ptr(buf, 4);
         ppc_maybe_bswap_register(env, mem_buf, 4);
         return 4;
     }
@@ -9921,28 +9924,31 @@ static int gdb_set_float_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int gdb_get_avr_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
+static int gdb_get_avr_reg(CPUPPCState *env, GByteArray *buf, int n)
 {
+    uint8_t *mem_buf;
+
     if (n < 32) {
         ppc_avr_t *avr = cpu_avr_ptr(env, n);
         if (!avr_need_swap(env)) {
-            stq_p(mem_buf, avr->u64[0]);
-            stq_p(mem_buf + 8, avr->u64[1]);
+            gdb_get_reg128(buf, avr->u64[0] , avr->u64[1]);
         } else {
-            stq_p(mem_buf, avr->u64[1]);
-            stq_p(mem_buf + 8, avr->u64[0]);
+            gdb_get_reg128(buf, avr->u64[1] , avr->u64[0]);
         }
+        mem_buf = gdb_get_reg_ptr(buf, 16);
         ppc_maybe_bswap_register(env, mem_buf, 8);
         ppc_maybe_bswap_register(env, mem_buf + 8, 8);
         return 16;
     }
     if (n == 32) {
-        stl_p(mem_buf, helper_mfvscr(env));
+        gdb_get_reg32(buf, helper_mfvscr(env));
+        mem_buf = gdb_get_reg_ptr(buf, 4);
         ppc_maybe_bswap_register(env, mem_buf, 4);
         return 4;
     }
     if (n == 33) {
-        stl_p(mem_buf, (uint32_t)env->spr[SPR_VRSAVE]);
+        gdb_get_reg32(buf, (uint32_t)env->spr[SPR_VRSAVE]);
+        mem_buf = gdb_get_reg_ptr(buf, 4);
         ppc_maybe_bswap_register(env, mem_buf, 4);
         return 4;
     }
@@ -9977,25 +9983,25 @@ static int gdb_set_avr_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int gdb_get_spe_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
+static int gdb_get_spe_reg(CPUPPCState *env, GByteArray *buf, int n)
 {
     if (n < 32) {
 #if defined(TARGET_PPC64)
-        stl_p(mem_buf, env->gpr[n] >> 32);
-        ppc_maybe_bswap_register(env, mem_buf, 4);
+        gdb_get_reg32(buf, env->gpr[n] >> 32);
+        ppc_maybe_bswap_register(env, gdb_get_reg_ptr(buf, 4), 4);
 #else
-        stl_p(mem_buf, env->gprh[n]);
+        gdb_get_reg32(buf, env->gprh[n]);
 #endif
         return 4;
     }
     if (n == 32) {
-        stq_p(mem_buf, env->spe_acc);
-        ppc_maybe_bswap_register(env, mem_buf, 8);
+        gdb_get_reg64(buf, env->spe_acc);
+        ppc_maybe_bswap_register(env, gdb_get_reg_ptr(buf, 8), 8);
         return 8;
     }
     if (n == 33) {
-        stl_p(mem_buf, env->spe_fscr);
-        ppc_maybe_bswap_register(env, mem_buf, 4);
+        gdb_get_reg32(buf, env->spe_fscr);
+        ppc_maybe_bswap_register(env, gdb_get_reg_ptr(buf, 4), 4);
         return 4;
     }
     return 0;
@@ -10030,11 +10036,11 @@ static int gdb_set_spe_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int gdb_get_vsx_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
+static int gdb_get_vsx_reg(CPUPPCState *env, GByteArray *buf, int n)
 {
     if (n < 32) {
-        stq_p(mem_buf, *cpu_vsrl_ptr(env, n));
-        ppc_maybe_bswap_register(env, mem_buf, 8);
+        gdb_get_reg64(buf, *cpu_vsrl_ptr(env, n));
+        ppc_maybe_bswap_register(env, gdb_get_reg_ptr(buf, 8), 8);
         return 8;
     }
     return 0;
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 3dcdf92227..31458c5b4a 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -293,7 +293,7 @@ extern const char * const riscv_excp_names[];
 extern const char * const riscv_intr_names[];
 
 void riscv_cpu_do_interrupt(CPUState *cpu);
-int riscv_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int riscv_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int riscv_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request);
 bool riscv_cpu_fp_enabled(CPURISCVState *env);
diff --git a/target/riscv/gdbstub.c b/target/riscv/gdbstub.c
index 2f32750f2f..eba12a86f2 100644
--- a/target/riscv/gdbstub.c
+++ b/target/riscv/gdbstub.c
@@ -270,7 +270,7 @@ static int csr_register_map[] = {
     CSR_MHCOUNTEREN,
 };
 
-int riscv_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int riscv_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
     CPURISCVState *env = &cpu->env;
@@ -301,14 +301,14 @@ int riscv_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int riscv_gdb_get_fpu(CPURISCVState *env, uint8_t *mem_buf, int n)
+static int riscv_gdb_get_fpu(CPURISCVState *env, GByteArray *buf, int n)
 {
     if (n < 32) {
         if (env->misa & RVD) {
-            return gdb_get_reg64(mem_buf, env->fpr[n]);
+            return gdb_get_reg64(buf, env->fpr[n]);
         }
         if (env->misa & RVF) {
-            return gdb_get_reg32(mem_buf, env->fpr[n]);
+            return gdb_get_reg32(buf, env->fpr[n]);
         }
     /* there is hole between ft11 and fflags in fpu.xml */
     } else if (n < 36 && n > 32) {
@@ -322,7 +322,7 @@ static int riscv_gdb_get_fpu(CPURISCVState *env, uint8_t *mem_buf, int n)
         result = riscv_csrrw_debug(env, n - 33 + csr_register_map[8], &val,
                                    0, 0);
         if (result == 0) {
-            return gdb_get_regl(mem_buf, val);
+            return gdb_get_regl(buf, val);
         }
     }
     return 0;
@@ -351,7 +351,7 @@ static int riscv_gdb_set_fpu(CPURISCVState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int riscv_gdb_get_csr(CPURISCVState *env, uint8_t *mem_buf, int n)
+static int riscv_gdb_get_csr(CPURISCVState *env, GByteArray *buf, int n)
 {
     if (n < ARRAY_SIZE(csr_register_map)) {
         target_ulong val = 0;
@@ -359,7 +359,7 @@ static int riscv_gdb_get_csr(CPURISCVState *env, uint8_t *mem_buf, int n)
 
         result = riscv_csrrw_debug(env, csr_register_map[n], &val, 0, 0);
         if (result == 0) {
-            return gdb_get_regl(mem_buf, val);
+            return gdb_get_regl(buf, val);
         }
     }
     return 0;
@@ -379,13 +379,13 @@ static int riscv_gdb_set_csr(CPURISCVState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-static int riscv_gdb_get_virtual(CPURISCVState *cs, uint8_t *mem_buf, int n)
+static int riscv_gdb_get_virtual(CPURISCVState *cs, GByteArray *buf, int n)
 {
     if (n == 0) {
 #ifdef CONFIG_USER_ONLY
-        return gdb_get_regl(mem_buf, 0);
+        return gdb_get_regl(buf, 0);
 #else
-        return gdb_get_regl(mem_buf, cs->priv);
+        return gdb_get_regl(buf, cs->priv);
 #endif
     }
     return 0;
diff --git a/target/s390x/gdbstub.c b/target/s390x/gdbstub.c
index e24a49f4a9..d6fce5ff1e 100644
--- a/target/s390x/gdbstub.c
+++ b/target/s390x/gdbstub.c
@@ -27,7 +27,7 @@
 #include "sysemu/hw_accel.h"
 #include "sysemu/tcg.h"
 
-int s390_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int s390_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     S390CPU *cpu = S390_CPU(cs);
     CPUS390XState *env = &cpu->env;
@@ -82,11 +82,11 @@ int s390_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
 /* total number of registers in s390-acr.xml */
 #define S390_NUM_AC_REGS 16
 
-static int cpu_read_ac_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
+static int cpu_read_ac_reg(CPUS390XState *env, GByteArray *buf, int n)
 {
     switch (n) {
     case S390_A0_REGNUM ... S390_A15_REGNUM:
-        return gdb_get_reg32(mem_buf, env->aregs[n]);
+        return gdb_get_reg32(buf, env->aregs[n]);
     default:
         return 0;
     }
@@ -111,13 +111,13 @@ static int cpu_write_ac_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
 /* total number of registers in s390-fpr.xml */
 #define S390_NUM_FP_REGS 17
 
-static int cpu_read_fp_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
+static int cpu_read_fp_reg(CPUS390XState *env, GByteArray *buf, int n)
 {
     switch (n) {
     case S390_FPC_REGNUM:
-        return gdb_get_reg32(mem_buf, env->fpc);
+        return gdb_get_reg32(buf, env->fpc);
     case S390_F0_REGNUM ... S390_F15_REGNUM:
-        return gdb_get_reg64(mem_buf, *get_freg(env, n - S390_F0_REGNUM));
+        return gdb_get_reg64(buf, *get_freg(env, n - S390_F0_REGNUM));
     default:
         return 0;
     }
@@ -145,17 +145,17 @@ static int cpu_write_fp_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
 /* total number of registers in s390-vx.xml */
 #define S390_NUM_VREGS 32
 
-static int cpu_read_vreg(CPUS390XState *env, uint8_t *mem_buf, int n)
+static int cpu_read_vreg(CPUS390XState *env, GByteArray *buf, int n)
 {
     int ret;
 
     switch (n) {
     case S390_V0L_REGNUM ... S390_V15L_REGNUM:
-        ret = gdb_get_reg64(mem_buf, env->vregs[n][1]);
+        ret = gdb_get_reg64(buf, env->vregs[n][1]);
         break;
     case S390_V16_REGNUM ... S390_V31_REGNUM:
-        ret = gdb_get_reg64(mem_buf, env->vregs[n][0]);
-        ret += gdb_get_reg64(mem_buf + 8, env->vregs[n][1]);
+        ret = gdb_get_reg64(buf, env->vregs[n][0]);
+        ret += gdb_get_reg64(buf, env->vregs[n][1]);
         break;
     default:
         ret = 0;
@@ -186,11 +186,11 @@ static int cpu_write_vreg(CPUS390XState *env, uint8_t *mem_buf, int n)
 #define S390_NUM_C_REGS 16
 
 #ifndef CONFIG_USER_ONLY
-static int cpu_read_c_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
+static int cpu_read_c_reg(CPUS390XState *env, GByteArray *buf, int n)
 {
     switch (n) {
     case S390_C0_REGNUM ... S390_C15_REGNUM:
-        return gdb_get_regl(mem_buf, env->cregs[n]);
+        return gdb_get_regl(buf, env->cregs[n]);
     default:
         return 0;
     }
@@ -223,7 +223,7 @@ static int cpu_write_c_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
 /* total number of registers in s390-virt.xml */
 #define S390_NUM_VIRT_REGS 8
 
-static int cpu_read_virt_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
+static int cpu_read_virt_reg(CPUS390XState *env, GByteArray *mem_buf, int n)
 {
     switch (n) {
     case S390_VIRT_CKC_REGNUM:
@@ -296,9 +296,9 @@ static int cpu_write_virt_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
 /* total number of registers in s390-gs.xml */
 #define S390_NUM_GS_REGS 4
 
-static int cpu_read_gs_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
+static int cpu_read_gs_reg(CPUS390XState *env, GByteArray *buf, int n)
 {
-    return gdb_get_regl(mem_buf, env->gscb[n]);
+    return gdb_get_regl(buf, env->gscb[n]);
 }
 
 static int cpu_write_gs_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
diff --git a/target/s390x/internal.h b/target/s390x/internal.h
index d37816104d..8c95c734db 100644
--- a/target/s390x/internal.h
+++ b/target/s390x/internal.h
@@ -292,7 +292,7 @@ uint16_t float128_dcmask(CPUS390XState *env, float128 f1);
 
 
 /* gdbstub.c */
-int s390_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int s390_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int s390_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void s390_cpu_gdb_init(CPUState *cs);
 
diff --git a/target/sh4/cpu.h b/target/sh4/cpu.h
index 452a596e67..dbe58c7888 100644
--- a/target/sh4/cpu.h
+++ b/target/sh4/cpu.h
@@ -208,7 +208,7 @@ void superh_cpu_do_interrupt(CPUState *cpu);
 bool superh_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void superh_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr superh_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int superh_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int superh_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int superh_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void superh_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
                                     MMUAccessType access_type,
diff --git a/target/sh4/gdbstub.c b/target/sh4/gdbstub.c
index 44c1679e9d..49fc4a0cc6 100644
--- a/target/sh4/gdbstub.c
+++ b/target/sh4/gdbstub.c
@@ -24,7 +24,7 @@
 /* Hint: Use "set architecture sh4" in GDB to see fpu registers */
 /* FIXME: We should use XML for this.  */
 
-int superh_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int superh_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     SuperHCPU *cpu = SUPERH_CPU(cs);
     CPUSH4State *env = &cpu->env;
diff --git a/target/sparc/cpu.h b/target/sparc/cpu.h
index ae97c7d9f7..b9369398f2 100644
--- a/target/sparc/cpu.h
+++ b/target/sparc/cpu.h
@@ -571,7 +571,7 @@ extern const VMStateDescription vmstate_sparc_cpu;
 void sparc_cpu_do_interrupt(CPUState *cpu);
 void sparc_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr sparc_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int sparc_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int sparc_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int sparc_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void QEMU_NORETURN sparc_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
                                                  MMUAccessType access_type,
diff --git a/target/sparc/gdbstub.c b/target/sparc/gdbstub.c
index 8be742b5a3..78dc8dcc98 100644
--- a/target/sparc/gdbstub.c
+++ b/target/sparc/gdbstub.c
@@ -27,7 +27,7 @@
 #define gdb_get_rega(buf, val) gdb_get_regl(buf, val)
 #endif
 
-int sparc_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int sparc_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     SPARCCPU *cpu = SPARC_CPU(cs);
     CPUSPARCState *env = &cpu->env;
diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h
index 493f4fc80c..c0d69fad96 100644
--- a/target/xtensa/cpu.h
+++ b/target/xtensa/cpu.h
@@ -569,7 +569,7 @@ void xtensa_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr xtensa_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
 void xtensa_count_regs(const XtensaConfig *config,
                        unsigned *n_regs, unsigned *n_core_regs);
-int xtensa_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int xtensa_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int xtensa_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void xtensa_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
                                     MMUAccessType access_type,
diff --git a/target/xtensa/gdbstub.c b/target/xtensa/gdbstub.c
index 54727881f3..0ee3feabe5 100644
--- a/target/xtensa/gdbstub.c
+++ b/target/xtensa/gdbstub.c
@@ -63,7 +63,7 @@ void xtensa_count_regs(const XtensaConfig *config,
     }
 }
 
-int xtensa_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int xtensa_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     XtensaCPU *cpu = XTENSA_CPU(cs);
     CPUXtensaState *env = &cpu->env;