At least for Cortex-M3 devices (but also M0, M0+, M4, ...), while
JTAG debugging using OpenOCD's built-in GDB server, the general purpose
register layout (i.e. `info reg' in GDB) should contain slightly more than
the usual ARM core registers.
The non-addressable core registers that appear in OpenOCD's listing are:
r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, sp (r13), lr (r14),
pc (r15), xpsr, primask, basepri, faultmask, and control.
These registers are well documented in the ARMv7M Architecture Reference
Manual.
This change addes preliminary support for those registers via a custom
qXfer:features:read+ and XML response that follows the GNU convention
documented here [1] for org.gnu.gdb.arm.m-profile and
org.gnu.gdb.arm.m-system.
[1] https://goo.gl/NMxlC5
The default behaviour for non-cortex-m will be to mimic the original ARM
behaviour of referring the GDB client to an <xi:include href="arm-core.xml">.
A simple test environment for this patch is to compile and link the following
assembly fragment:
.syntax unified
.cpu cortex-m3
.section .interp
.word 0x20020000
.word 0x9
.text
.global _start
.thumb
.thumb_func
.type _start, %function
_start:
b _start
.size _start, .-_start
Using the command below:
arm-none-eabi-gcc -g -O0 -mthumb -march=armv7-m -Wl,-Ttext-segment,0 \
-static -nostartfiles -o foo foo.S
Launch the resulting binary with qemu:
qemu-system-arm -S -s -M netduino2 -nographic -kernel foo
Run gdb, attaching to the qemu's GDB server:
arm-none-eabi-gdb foo
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
0x00000000 in _start ()
(gdb) info all-registers
r0 0x0 0
r1 0x0 0
r2 0x0 0
r3 0x0 0
r4 0x0 0
r5 0x0 0
r6 0x0 0
r7 0x0 0
r8 0x0 0
r9 0x0 0
r10 0x0 0
r11 0x0 0
r12 0x0 0
sp 0xbffef7fc 0xbffef7fc
lr 0x0 0
pc 0x0 0x0 <_start>
xpsr 0x40000000 1073741824
msp 0xbffef7fc 0xbffef7fc
psp 0x0 0x0 <_start>
primask 0x0 0
basepri 0x0 0
faultmask 0x1 1
control 0x0 0
The changes have been tested with other firmware images and also via Eclipse
Mars.
Christopher Friedt (1):
qemu-system-arm: cortex-m gdb registers
gdbstub.c | 29 ++++---
include/qom/cpu.h | 1 +
target-arm/cpu-qom.h | 4 +
target-arm/cpu.c | 5 +-
target-arm/gdbstub.c | 215 +++++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 241 insertions(+), 13 deletions(-)
--
2.5.4 (Apple Git-61)
