Otherwise, a serial port can get stuck if it is migrated while flow control
is in effect.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/char/serial.c | 16 ++++++++++++++--
include/hw/char/serial.h | 1 +
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/hw/char/serial.c b/hw/char/serial.c
index e65e9e0..6f0a49e 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -639,8 +639,20 @@ static int serial_post_load(void *opaque, int version_id)
if (s->thr_ipending == -1) {
s->thr_ipending = ((s->iir & UART_IIR_ID) == UART_IIR_THRI);
}
- if (s->tsr_retry > MAX_XMIT_RETRY) {
- s->tsr_retry = MAX_XMIT_RETRY;
+
+ if (s->tsr_retry > 0) {
+ /* tsr_retry > 0 implies LSR.TEMT = 0 (transmitter not empty). */
+ if (s->lsr & UART_LSR_TEMT) {
+ return -1;
+ }
+
+ assert(s->watch_tag == 0);
+ s->watch_tag = qemu_chr_fe_add_watch(s->chr, G_IO_OUT|G_IO_HUP,
serial_xmit, s);
+ } else {
+ /* tsr_retry == 0 implies LSR.TEMT = 1 (transmitter empty). */
+ if (!(s->lsr & UART_LSR_TEMT)) {
+ return -1;
+ }
}
s->last_break_enable = (s->lcr >> 6) & 1;
diff --git a/include/hw/char/serial.h b/include/hw/char/serial.h
index ef90615..2ab835c 100644
--- a/include/hw/char/serial.h
+++ b/include/hw/char/serial.h
@@ -56,6 +56,7 @@ struct SerialState {
int it_shift;
int baudbase;
unsigned tsr_retry;
+ unsigned watch_tag;
uint32_t wakeup;
/* Time when the last byte was successfully sent out of the tsr */
--
2.5.5
