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serial: chardev hotswap support 

This allows to change the port's backend runtime, e.g. change it from
file to a socket making it possible to establish a debug session with
WinDbg

> qemu-system [..] -chardev file,id=charchannel2,path=/tmp/charchannel2 \
  -device isa-serial,chardev=charchannel2,id=channel2

QEMU 2.9.50 monitor - type 'help' for more information
(qemu) chardev-change charchannel2 \
  socket,host=127.0.0.1,port=4242,server,nowait

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 <anton.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <1499342940-56739-14-git-send-email-anton.nefedov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Anton Nefedov 2017-07-06 15:09:00 +03:00 committed by Paolo Bonzini
parent 757358425e
commit 1a29cc8f5e
1 changed files with 29 additions and 1 deletions
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30
hw/char/serial.c
View File

@ -891,6 +891,34 @@ 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_backend_connected(&s->chr)) {
@ -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);