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Re: [Qemu-devel] [PATCH v4 13/13] serial: chardev hotswap support


From: Anton Nefedov
Subject: Re: [Qemu-devel] [PATCH v4 13/13] serial: chardev hotswap support
Date: Mon, 3 Jul 2017 14:52:29 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1

Hi Paolo, Michael,

Any feedback on this change? (and a cosmetic patch 12 of this series)

Thanks a lot in advance,


/Anton

On 06/26/2017 07:45 PM, Anton Nefedov wrote:
for a backend change, a number of ioctls has to be replayed to sync
the current setup of a frontend to a backend tty. This is hopefully
enough so we don't have to track, store and replay the whole original
control byte sequence.

Signed-off-by: Anton Nefedov <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
CC: Michael S. Tsirkin <address@hidden>
CC: Paolo Bonzini <address@hidden>
---
  hw/char/serial.c | 32 ++++++++++++++++++++++++++++++--
  1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/hw/char/serial.c b/hw/char/serial.c
index e47f0b6..9aec6c6 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -891,9 +891,37 @@ static void serial_reset(void *opaque)
      s->msr &= ~UART_MSR_ANY_DELTA;
  }
+static int serial_be_change(void *opaque)
+{
+    SerialState *s = opaque;
+
+    qemu_chr_fe_set_handlers(&s->chr, serial_can_receive1, serial_receive1,
+                             serial_event, serial_be_change, s, NULL, true);
+
+    serial_update_parameters(s);
+
+    qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
+                      &s->last_break_enable);
+
+    s->poll_msl = (s->ier & UART_IER_MSI) ? 1 : 0;
+    serial_update_msl(s);
+
+    if (s->poll_msl >= 0 && !(s->mcr & UART_MCR_LOOP)) {
+        serial_update_tiocm(s);
+    }
+
+    if (s->watch_tag > 0) {
+        g_source_remove(s->watch_tag);
+        s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
+                                             serial_watch_cb, s);
+    }
+
+    return 0;
+}
+
  void serial_realize_core(SerialState *s, Error **errp)
  {
-    if (!qemu_chr_fe_get_driver(&s->chr)) {
+    if (!qemu_chr_fe_backend_connected(&s->chr)) {
          error_setg(errp, "Can't create serial device, empty char device");
          return;
      }
@@ -904,7 +932,7 @@ void serial_realize_core(SerialState *s, Error **errp)
      qemu_register_reset(serial_reset, s);
qemu_chr_fe_set_handlers(&s->chr, serial_can_receive1, serial_receive1,
-                             serial_event, NULL, s, NULL, true);
+                             serial_event, serial_be_change, s, NULL, true);
      fifo8_create(&s->recv_fifo, UART_FIFO_LENGTH);
      fifo8_create(&s->xmit_fifo, UART_FIFO_LENGTH);
      serial_reset(s);





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