This will greatly enhance the usefulness of QEMU virtual serial ports, because
the Linux kernel interprets a break on the serial console as a SysRq, but there
is currently no way to pass this signal over a pseudo-terminal. This patch will
work for transmitting BREAK from master to slave through pseudo-terminal.
Signed-off-by: Nan Li <n...@suse.com>
---
drivers/tty/pty.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index e72ee62..ac8893a 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -31,6 +31,7 @@
static struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
static DEFINE_MUTEX(devpts_mutex);
+#define BREAK_STRING '\0'
#endif
static void pty_close(struct tty_struct *tty, struct file *filp)
@@ -674,6 +675,23 @@ static void pty_unix98_shutdown(struct tty_struct *tty)
devpts_kill_index(tty->driver_data, tty->index);
}
+static int pty_unix98_break_ctl(struct tty_struct *tty, int break_state)
+{
+ int c;
+ struct tty_struct *to = tty->link;
+
+ if (break_state) {
+ /* Stuff the break data into the input queue of the other end */
+ c = tty_insert_flip_char(to->port, BREAK_STRING, TTY_BREAK);
+ /* And shovel */
+ if (c)
+ tty_flip_buffer_push(to->port);
+ else
+ return -ENOMEM;
+ }
+ return 0;
+}
+
static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
.install = pty_unix98_install,
@@ -686,6 +704,7 @@ static const struct tty_operations ptm_unix98_ops = {
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.ioctl = pty_unix98_ioctl,
+ .break_ctl = pty_unix98_break_ctl,
.resize = pty_resize,
.shutdown = pty_unix98_shutdown,
.cleanup = pty_cleanup
--
1.7.12.4
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