On 21 May 2018 at 13:25, Peter Maydell <peter.mayd...@linaro.org> wrote: > On 21 May 2018 at 13:21, Michael Walle <mich...@walle.cc> wrote: >> Changing the IP/IM registers may cause interrupts, so hold the BQL. >> >> Cc: qemu-sta...@nongnu.org >> Signed-off-by: Michael Walle <mich...@walle.cc> >> --- >> target/lm32/gdbstub.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/target/lm32/gdbstub.c b/target/lm32/gdbstub.c >> index cf929dd392..dac9418a2b 100644 >> --- a/target/lm32/gdbstub.c >> +++ b/target/lm32/gdbstub.c >> @@ -18,6 +18,7 @@ >> * License along with this library; if not, see >> <http://www.gnu.org/licenses/>. >> */ >> #include "qemu/osdep.h" >> +#include "qemu/main-loop.h" >> #include "qemu-common.h" >> #include "cpu.h" >> #include "exec/gdbstub.h" >> @@ -82,10 +83,14 @@ int lm32_cpu_gdb_write_register(CPUState *cs, uint8_t >> *mem_buf, int n) >> env->ie = tmp; >> break; >> case 37: >> + qemu_mutex_lock_iothread(); >> lm32_pic_set_im(env->pic_state, tmp); >> + qemu_mutex_unlock_iothread(); >> break; >> case 38: >> + qemu_mutex_lock_iothread(); >> lm32_pic_set_ip(env->pic_state, tmp); >> + qemu_mutex_unlock_iothread(); >> break; >> } >> } > > Are you sure this is necessary? I would have expected the gdbstub to > be operating under the qemu lock anyway.
...experimentation suggests that the gdbstub is called via chardev write events which are triggered by glib_pollfds_poll(), which is called by os_host_main_loop_wait() only when it holds the iothread lock. thanks -- PMM
