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[binutils-gdb] Support Z0 packet in AArch64 multi-arch debugging
- From: Yao Qi <qiyao at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 7 Dec 2015 15:57:54 -0000
- Subject: [binutils-gdb] Support Z0 packet in AArch64 multi-arch debugging
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=17b1509aac6ff4205749c2626fddbb1c4d7255f4
commit 17b1509aac6ff4205749c2626fddbb1c4d7255f4
Author: Yao Qi <yao.qi@linaro.org>
Date: Mon Dec 7 15:56:31 2015 +0000
Support Z0 packet in AArch64 multi-arch debugging
In commit 6085d6f6, Z0 packet is disabled in aarch64 GDBserver if
the inferior is 32-bit or there may be multiple inferiors, because
Z0 packet isn't supported for arm then. Recently, Z0 packet
is supported in arm target, so we don't have such limitation in
aarch64 GDBserver, that is to say, aarch64 GDBserver can use Z0
packet in multi-arch/multi-inferior debugging when the inferior's
arch is arm.
Part of this patch is to revert 6085d6f6, and the rest of the patch
is to move some breakpoint related arm_* functions into
linux-aarch32-low.c in order to share them between arm and aarch64.
This patch is regression tested on aarch64-linux for debugging both
aarch64 programs and arm programs respectively.
gdb/gdbserver:
2015-12-07 Yao Qi <yao.qi@linaro.org>
* configure.srv: Append arm.o to srv_tgtobj for
aarch64*-*-linux* target.
* linux-aarch32-low.c (arm_abi_breakpoint): New macro. Moved
from linux-arm-low.c.
(arm_eabi_breakpoint, arm_breakpoint): Likewise.
(arm_breakpoint_len, thumb_breakpoint): Likewise.
(thumb_breakpoint_len, thumb2_breakpoint): Likewise.
(thumb2_breakpoint_len): Likewise.
(arm_is_thumb_mode, arm_breakpoint_at): Likewise.
(arm_breakpoint_kinds): Likewise.
(arm_breakpoint_kind_from_pc): Likewise.
(arm_sw_breakpoint_from_kind): Likewise.
(arm_breakpoint_kind_from_current_state): Likewise.
* linux-aarch32-low.h (arm_breakpoint_kind_from_pc): Declare.
(arm_sw_breakpoint_from_kind): Declare.
(arm_breakpoint_kind_from_current_state): Declare.
(arm_breakpoint_at): Declare.
* linux-aarch64-low.c (aarch64_sw_breakpoint_from_kind): Call
arm_sw_breakpoint_from_kind if process is 32-bit.
(aarch64_breakpoint_kind_from_pc): New function.
(aarch64_breakpoint_kind_from_current_state): New function.
(the_low_target): Initialize fields breakpoint_kind_from_pc
and breakpoint_kind_from_current_state.
* linux-arm-low.c (arm_breakpoint_kinds): Move to
linux-aarch32-low.c.
(arm_abi_breakpoint, arm_eabi_breakpoint): Likewise.
(arm_breakpoint, arm_breakpoint_len): Likewise.
(thumb_breakpoint, thumb_breakpoint_len): Likewise.
(thumb2_breakpoint, thumb2_breakpoint_len): Likewise.
(arm_is_thumb_mode): Likewise.
(arm_breakpoint_at): Likewise.
(arm_breakpoint_kind_from_pc): Likewise.
(arm_sw_breakpoint_from_kind): Likewise.
(arm_breakpoint_kind_from_current_state): Likewise.
Revert:
2015-08-04 Yao Qi <yao.qi@linaro.org>
* linux-aarch64-low.c (aarch64_supports_z_point_type): Return
0 for Z_PACKET_SW_BP if it may be used in multi-arch debugging.
* server.c (extended_protocol): Remove "static".
* server.h (extended_protocol): Declare it.
Diff:
---
gdb/gdbserver/ChangeLog | 45 +++++++++++
gdb/gdbserver/configure.srv | 1 +
gdb/gdbserver/linux-aarch32-low.c | 159 ++++++++++++++++++++++++++++++++++++++
gdb/gdbserver/linux-aarch32-low.h | 5 ++
gdb/gdbserver/linux-aarch64-low.c | 52 ++++++++-----
gdb/gdbserver/linux-arm-low.c | 159 --------------------------------------
gdb/gdbserver/server.c | 2 +-
gdb/gdbserver/server.h | 1 -
8 files changed, 243 insertions(+), 181 deletions(-)
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 55648bc..7f7b6c1 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,48 @@
+2015-12-07 Yao Qi <yao.qi@linaro.org>
+
+ * configure.srv: Append arm.o to srv_tgtobj for
+ aarch64*-*-linux* target.
+ * linux-aarch32-low.c (arm_abi_breakpoint): New macro. Moved
+ from linux-arm-low.c.
+ (arm_eabi_breakpoint, arm_breakpoint): Likewise.
+ (arm_breakpoint_len, thumb_breakpoint): Likewise.
+ (thumb_breakpoint_len, thumb2_breakpoint): Likewise.
+ (thumb2_breakpoint_len): Likewise.
+ (arm_is_thumb_mode, arm_breakpoint_at): Likewise.
+ (arm_breakpoint_kinds): Likewise.
+ (arm_breakpoint_kind_from_pc): Likewise.
+ (arm_sw_breakpoint_from_kind): Likewise.
+ (arm_breakpoint_kind_from_current_state): Likewise.
+ * linux-aarch32-low.h (arm_breakpoint_kind_from_pc): Declare.
+ (arm_sw_breakpoint_from_kind): Declare.
+ (arm_breakpoint_kind_from_current_state): Declare.
+ (arm_breakpoint_at): Declare.
+ * linux-aarch64-low.c (aarch64_sw_breakpoint_from_kind): Call
+ arm_sw_breakpoint_from_kind if process is 32-bit.
+ (aarch64_breakpoint_kind_from_pc): New function.
+ (aarch64_breakpoint_kind_from_current_state): New function.
+ (the_low_target): Initialize fields breakpoint_kind_from_pc
+ and breakpoint_kind_from_current_state.
+ * linux-arm-low.c (arm_breakpoint_kinds): Move to
+ linux-aarch32-low.c.
+ (arm_abi_breakpoint, arm_eabi_breakpoint): Likewise.
+ (arm_breakpoint, arm_breakpoint_len): Likewise.
+ (thumb_breakpoint, thumb_breakpoint_len): Likewise.
+ (thumb2_breakpoint, thumb2_breakpoint_len): Likewise.
+ (arm_is_thumb_mode): Likewise.
+ (arm_breakpoint_at): Likewise.
+ (arm_breakpoint_kind_from_pc): Likewise.
+ (arm_sw_breakpoint_from_kind): Likewise.
+ (arm_breakpoint_kind_from_current_state): Likewise.
+
+ Revert:
+ 2015-08-04 Yao Qi <yao.qi@linaro.org>
+
+ * linux-aarch64-low.c (aarch64_supports_z_point_type): Return
+ 0 for Z_PACKET_SW_BP if it may be used in multi-arch debugging.
+ * server.c (extended_protocol): Remove "static".
+ * server.h (extended_protocol): Declare it.
+
2015-12-04 Josh Stone <jistone@redhat.com>
* target.h (struct target_ops) <arch_setup>: Rename to ...
diff --git a/gdb/gdbserver/configure.srv b/gdb/gdbserver/configure.srv
index e854110..6dfd6e0 100644
--- a/gdb/gdbserver/configure.srv
+++ b/gdb/gdbserver/configure.srv
@@ -52,6 +52,7 @@ case "${target}" in
srv_regobj="${srv_regobj} arm-with-neon.o"
srv_tgtobj="linux-aarch64-low.o aarch64-linux-hw-point.o"
srv_tgtobj="$srv_tgtobj linux-aarch32-low.o"
+ srv_tgtobj="${srv_tgtobj} arm.o"
srv_tgtobj="$srv_tgtobj aarch64-linux.o"
srv_tgtobj="$srv_tgtobj aarch64-insn.o"
srv_tgtobj="${srv_tgtobj} $srv_linux_obj"
diff --git a/gdb/gdbserver/linux-aarch32-low.c b/gdb/gdbserver/linux-aarch32-low.c
index 221b5b9..7379350 100644
--- a/gdb/gdbserver/linux-aarch32-low.c
+++ b/gdb/gdbserver/linux-aarch32-low.c
@@ -137,6 +137,165 @@ struct regs_info regs_info_aarch32 =
&aarch32_regsets_info
};
+/* Correct in either endianness. */
+#define arm_abi_breakpoint 0xef9f0001UL
+
+/* For new EABI binaries. We recognize it regardless of which ABI
+ is used for gdbserver, so single threaded debugging should work
+ OK, but for multi-threaded debugging we only insert the current
+ ABI's breakpoint instruction. For now at least. */
+#define arm_eabi_breakpoint 0xe7f001f0UL
+
+#ifndef __ARM_EABI__
+static const unsigned long arm_breakpoint = arm_abi_breakpoint;
+#else
+static const unsigned long arm_breakpoint = arm_eabi_breakpoint;
+#endif
+
+#define arm_breakpoint_len 4
+static const unsigned short thumb_breakpoint = 0xde01;
+#define thumb_breakpoint_len 2
+static const unsigned short thumb2_breakpoint[] = { 0xf7f0, 0xa000 };
+#define thumb2_breakpoint_len 4
+
+/* Returns 1 if the current instruction set is thumb, 0 otherwise. */
+
+static int
+arm_is_thumb_mode (void)
+{
+ struct regcache *regcache = get_thread_regcache (current_thread, 1);
+ unsigned long cpsr;
+
+ collect_register_by_name (regcache, "cpsr", &cpsr);
+
+ if (cpsr & 0x20)
+ return 1;
+ else
+ return 0;
+}
+
+/* Returns 1 if there is a software breakpoint at location. */
+
+int
+arm_breakpoint_at (CORE_ADDR where)
+{
+ if (arm_is_thumb_mode ())
+ {
+ /* Thumb mode. */
+ unsigned short insn;
+
+ (*the_target->read_memory) (where, (unsigned char *) &insn, 2);
+ if (insn == thumb_breakpoint)
+ return 1;
+
+ if (insn == thumb2_breakpoint[0])
+ {
+ (*the_target->read_memory) (where + 2, (unsigned char *) &insn, 2);
+ if (insn == thumb2_breakpoint[1])
+ return 1;
+ }
+ }
+ else
+ {
+ /* ARM mode. */
+ unsigned long insn;
+
+ (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
+ if (insn == arm_abi_breakpoint)
+ return 1;
+
+ if (insn == arm_eabi_breakpoint)
+ return 1;
+ }
+
+ return 0;
+}
+
+/* Enum describing the different kinds of breakpoints. */
+enum arm_breakpoint_kinds
+{
+ ARM_BP_KIND_THUMB = 2,
+ ARM_BP_KIND_THUMB2 = 3,
+ ARM_BP_KIND_ARM = 4,
+};
+
+/* Implementation of linux_target_ops method "breakpoint_kind_from_pc".
+
+ Determine the type and size of breakpoint to insert at PCPTR. Uses the
+ program counter value to determine whether a 16-bit or 32-bit breakpoint
+ should be used. It returns the breakpoint's kind, and adjusts the program
+ counter (if necessary) to point to the actual memory location where the
+ breakpoint should be inserted. */
+
+int
+arm_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
+{
+ if (IS_THUMB_ADDR (*pcptr))
+ {
+ gdb_byte buf[2];
+
+ *pcptr = UNMAKE_THUMB_ADDR (*pcptr);
+
+ /* Check whether we are replacing a thumb2 32-bit instruction. */
+ if ((*the_target->read_memory) (*pcptr, buf, 2) == 0)
+ {
+ unsigned short inst1 = 0;
+
+ (*the_target->read_memory) (*pcptr, (gdb_byte *) &inst1, 2);
+ if (thumb_insn_size (inst1) == 4)
+ return ARM_BP_KIND_THUMB2;
+ }
+ return ARM_BP_KIND_THUMB;
+ }
+ else
+ return ARM_BP_KIND_ARM;
+}
+
+/* Implementation of the linux_target_ops method "sw_breakpoint_from_kind". */
+
+const gdb_byte *
+arm_sw_breakpoint_from_kind (int kind , int *size)
+{
+ *size = arm_breakpoint_len;
+ /* Define an ARM-mode breakpoint; we only set breakpoints in the C
+ library, which is most likely to be ARM. If the kernel supports
+ clone events, we will never insert a breakpoint, so even a Thumb
+ C library will work; so will mixing EABI/non-EABI gdbserver and
+ application. */
+ switch (kind)
+ {
+ case ARM_BP_KIND_THUMB:
+ *size = thumb_breakpoint_len;
+ return (gdb_byte *) &thumb_breakpoint;
+ case ARM_BP_KIND_THUMB2:
+ *size = thumb2_breakpoint_len;
+ return (gdb_byte *) &thumb2_breakpoint;
+ case ARM_BP_KIND_ARM:
+ *size = arm_breakpoint_len;
+ return (const gdb_byte *) &arm_breakpoint;
+ default:
+ return NULL;
+ }
+ return NULL;
+}
+
+/* Implementation of the linux_target_ops method
+ "breakpoint_kind_from_current_state". */
+
+int
+arm_breakpoint_kind_from_current_state (CORE_ADDR *pcptr)
+{
+ if (arm_is_thumb_mode ())
+ {
+ *pcptr = MAKE_THUMB_ADDR (*pcptr);
+ return arm_breakpoint_kind_from_pc (pcptr);
+ }
+ else
+ {
+ return arm_breakpoint_kind_from_pc (pcptr);
+ }
+}
+
void
initialize_low_arch_aarch32 (void)
{
diff --git a/gdb/gdbserver/linux-aarch32-low.h b/gdb/gdbserver/linux-aarch32-low.h
index 6682f0a..0afddc8 100644
--- a/gdb/gdbserver/linux-aarch32-low.h
+++ b/gdb/gdbserver/linux-aarch32-low.h
@@ -23,6 +23,11 @@ void arm_fill_vfpregset_num (struct regcache *regcache, void *buf, int num);
void arm_store_vfpregset_num (struct regcache *regcache, const void *buf,
int num);
+int arm_breakpoint_kind_from_pc (CORE_ADDR *pcptr);
+const gdb_byte *arm_sw_breakpoint_from_kind (int kind , int *size);
+int arm_breakpoint_kind_from_current_state (CORE_ADDR *pcptr);
+int arm_breakpoint_at (CORE_ADDR where);
+
void initialize_low_arch_aarch32 (void);
void init_registers_arm_with_neon (void);
diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
index 17798ff..5fd3f51 100644
--- a/gdb/gdbserver/linux-aarch64-low.c
+++ b/gdb/gdbserver/linux-aarch64-low.c
@@ -260,22 +260,6 @@ aarch64_supports_z_point_type (char z_type)
switch (z_type)
{
case Z_PACKET_SW_BP:
- {
- if (!extended_protocol && is_64bit_tdesc ())
- {
- /* Only enable Z0 packet in non-multi-arch debugging. If
- extended protocol is used, don't enable Z0 packet because
- GDBserver may attach to 32-bit process. */
- return 1;
- }
- else
- {
- /* Disable Z0 packet so that GDBserver doesn't have to handle
- different breakpoint instructions (aarch64, arm, thumb etc)
- in multi-arch debugging. */
- return 0;
- }
- }
case Z_PACKET_HW_BP:
case Z_PACKET_WRITE_WP:
case Z_PACKET_READ_WP:
@@ -2940,8 +2924,36 @@ aarch64_supports_range_stepping (void)
static const gdb_byte *
aarch64_sw_breakpoint_from_kind (int kind, int *size)
{
- *size = aarch64_breakpoint_len;
- return aarch64_breakpoint;
+ if (is_64bit_tdesc ())
+ {
+ *size = aarch64_breakpoint_len;
+ return aarch64_breakpoint;
+ }
+ else
+ return arm_sw_breakpoint_from_kind (kind, size);
+}
+
+/* Implementation of linux_target_ops method "breakpoint_kind_from_pc". */
+
+static int
+aarch64_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
+{
+ if (is_64bit_tdesc ())
+ return aarch64_breakpoint_len;
+ else
+ return arm_breakpoint_kind_from_pc (pcptr);
+}
+
+/* Implementation of the linux_target_ops method
+ "breakpoint_kind_from_current_state". */
+
+static int
+aarch64_breakpoint_kind_from_current_state (CORE_ADDR *pcptr)
+{
+ if (is_64bit_tdesc ())
+ return aarch64_breakpoint_len;
+ else
+ return arm_breakpoint_kind_from_current_state (pcptr);
}
/* Support for hardware single step. */
@@ -2961,7 +2973,7 @@ struct linux_target_ops the_low_target =
NULL, /* fetch_register */
aarch64_get_pc,
aarch64_set_pc,
- NULL, /* breakpoint_kind_from_pc */
+ aarch64_breakpoint_kind_from_pc,
aarch64_sw_breakpoint_from_kind,
NULL, /* breakpoint_reinsert_addr */
0, /* decr_pc_after_break */
@@ -2985,7 +2997,7 @@ struct linux_target_ops the_low_target =
aarch64_emit_ops,
aarch64_get_min_fast_tracepoint_insn_len,
aarch64_supports_range_stepping,
- NULL, /* breakpoint_kind_from_current_state */
+ aarch64_breakpoint_kind_from_current_state,
aarch64_supports_hardware_single_step,
};
diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
index 7703008..d4d58a8 100644
--- a/gdb/gdbserver/linux-arm-low.c
+++ b/gdb/gdbserver/linux-arm-low.c
@@ -80,14 +80,6 @@ typedef enum
arm_hwbp_access = 3
} arm_hwbp_type;
-/* Enum describing the different kinds of breakpoints. */
-enum arm_breakpoint_kinds
-{
- ARM_BP_KIND_THUMB = 2,
- ARM_BP_KIND_THUMB2 = 3,
- ARM_BP_KIND_ARM = 4,
-};
-
/* Type describing an ARM Hardware Breakpoint Control register value. */
typedef unsigned int arm_hwbp_control_t;
@@ -241,80 +233,6 @@ arm_set_pc (struct regcache *regcache, CORE_ADDR pc)
supply_register_by_name (regcache, "pc", &newpc);
}
-/* Correct in either endianness. */
-#define arm_abi_breakpoint 0xef9f0001UL
-
-/* For new EABI binaries. We recognize it regardless of which ABI
- is used for gdbserver, so single threaded debugging should work
- OK, but for multi-threaded debugging we only insert the current
- ABI's breakpoint instruction. For now at least. */
-#define arm_eabi_breakpoint 0xe7f001f0UL
-
-#ifndef __ARM_EABI__
-static const unsigned long arm_breakpoint = arm_abi_breakpoint;
-#else
-static const unsigned long arm_breakpoint = arm_eabi_breakpoint;
-#endif
-
-#define arm_breakpoint_len 4
-static const unsigned short thumb_breakpoint = 0xde01;
-#define thumb_breakpoint_len 2
-static const unsigned short thumb2_breakpoint[] = { 0xf7f0, 0xa000 };
-#define thumb2_breakpoint_len 4
-
-/* Returns 1 if the current instruction set is thumb, 0 otherwise. */
-
-static int
-arm_is_thumb_mode (void)
-{
- struct regcache *regcache = get_thread_regcache (current_thread, 1);
- unsigned long cpsr;
-
- collect_register_by_name (regcache, "cpsr", &cpsr);
-
- if (cpsr & 0x20)
- return 1;
- else
- return 0;
-}
-
-/* Returns 1 if there is a software breakpoint at location. */
-
-static int
-arm_breakpoint_at (CORE_ADDR where)
-{
- if (arm_is_thumb_mode ())
- {
- /* Thumb mode. */
- unsigned short insn;
-
- (*the_target->read_memory) (where, (unsigned char *) &insn, 2);
- if (insn == thumb_breakpoint)
- return 1;
-
- if (insn == thumb2_breakpoint[0])
- {
- (*the_target->read_memory) (where + 2, (unsigned char *) &insn, 2);
- if (insn == thumb2_breakpoint[1])
- return 1;
- }
- }
- else
- {
- /* ARM mode. */
- unsigned long insn;
-
- (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
- if (insn == arm_abi_breakpoint)
- return 1;
-
- if (insn == arm_eabi_breakpoint)
- return 1;
- }
-
- return 0;
-}
-
/* Fetch the thread-local storage pointer for libthread_db. */
ps_err_e
@@ -943,83 +861,6 @@ arm_regs_info (void)
return ®s_info_arm;
}
-/* Implementation of linux_target_ops method "breakpoint_kind_from_pc".
-
- Determine the type and size of breakpoint to insert at PCPTR. Uses the
- program counter value to determine whether a 16-bit or 32-bit breakpoint
- should be used. It returns the breakpoint's kind, and adjusts the program
- counter (if necessary) to point to the actual memory location where the
- breakpoint should be inserted. */
-
-static int
-arm_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
-{
- if (IS_THUMB_ADDR (*pcptr))
- {
- gdb_byte buf[2];
-
- *pcptr = UNMAKE_THUMB_ADDR (*pcptr);
-
- /* Check whether we are replacing a thumb2 32-bit instruction. */
- if ((*the_target->read_memory) (*pcptr, buf, 2) == 0)
- {
- unsigned short inst1 = 0;
-
- (*the_target->read_memory) (*pcptr, (gdb_byte *) &inst1, 2);
- if (thumb_insn_size (inst1) == 4)
- return ARM_BP_KIND_THUMB2;
- }
- return ARM_BP_KIND_THUMB;
- }
- else
- return ARM_BP_KIND_ARM;
-}
-
-/* Implementation of the linux_target_ops method "sw_breakpoint_from_kind". */
-
-static const gdb_byte *
-arm_sw_breakpoint_from_kind (int kind , int *size)
-{
- *size = arm_breakpoint_len;
- /* Define an ARM-mode breakpoint; we only set breakpoints in the C
- library, which is most likely to be ARM. If the kernel supports
- clone events, we will never insert a breakpoint, so even a Thumb
- C library will work; so will mixing EABI/non-EABI gdbserver and
- application. */
- switch (kind)
- {
- case ARM_BP_KIND_THUMB:
- *size = thumb_breakpoint_len;
- return (gdb_byte *) &thumb_breakpoint;
- case ARM_BP_KIND_THUMB2:
- *size = thumb2_breakpoint_len;
- return (gdb_byte *) &thumb2_breakpoint;
- case ARM_BP_KIND_ARM:
- *size = arm_breakpoint_len;
- return (const gdb_byte *) &arm_breakpoint;
- default:
- return NULL;
- }
- return NULL;
-}
-
-/* Implementation of the linux_target_ops method
- "breakpoint_kind_from_current_state". */
-
-static int
-arm_breakpoint_kind_from_current_state (CORE_ADDR *pcptr)
-{
- if (arm_is_thumb_mode ())
- {
- *pcptr = MAKE_THUMB_ADDR (*pcptr);
- return arm_breakpoint_kind_from_pc (pcptr);
- }
- else
- {
- return arm_breakpoint_kind_from_pc (pcptr);
- }
-}
-
struct linux_target_ops the_low_target = {
arm_arch_setup,
arm_regs_info,
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 6d151ee..a09841c 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -49,7 +49,7 @@ ptid_t general_thread;
int server_waiting;
-int extended_protocol;
+static int extended_protocol;
static int response_needed;
static int exit_requested;
diff --git a/gdb/gdbserver/server.h b/gdb/gdbserver/server.h
index dc0361f..18095f2 100644
--- a/gdb/gdbserver/server.h
+++ b/gdb/gdbserver/server.h
@@ -89,7 +89,6 @@ extern int report_vfork_events;
extern int report_exec_events;
extern int report_thread_events;
extern int non_stop;
-extern int extended_protocol;
/* True if the "swbreak+" feature is active. In that case, GDB wants
us to report whether a trap is explained by a software breakpoint