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Re: [Qemu-devel] [PATCH v2 1/2] trap signals for "-serial mon:stdio"
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] trap signals for "-serial mon:stdio" |
Date: |
Wed, 03 Jul 2013 09:13:58 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 03/07/2013 08:44, Michael Tokarev ha scritto:
> From: Paolo Bonzini <address@hidden>
>
> With mon:stdio you can exit the VM by switching to the monitor and
> sending the "quit" command. It is then useful to pass Ctrl-C to the
> VM instead of exiting.
>
> This in turn lets us stop tying the default signal handling behavior
> to -nographic, removing gratuitous differences between "-display none"
> and "-nographic".
>
> This patch changes behavior for "-display none -serial mon:stdio", as
> expected, but not for "-display none -serial stdio".
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> Signed-off-by: Michael Tokarev <address@hidden>
> ---
> V2: added code comments and documentation fixes by mjt
> (hopefully the s-o-b stands still)
>
> qemu-char.c | 13 +++++++++----
> qemu-options.hx | 8 +++++---
> 2 files changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/qemu-char.c b/qemu-char.c
> index 6cec5d7..18c42a3 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -926,7 +926,6 @@ static void qemu_chr_set_echo_stdio(CharDriverState *chr,
> bool echo)
> tty.c_cc[VMIN] = 1;
> tty.c_cc[VTIME] = 0;
> }
> - /* if graphical mode, we allow Ctrl-C handling */
> if (!stdio_allow_signal)
> tty.c_lflag &= ~ISIG;
>
> @@ -955,7 +954,6 @@ static CharDriverState *qemu_chr_open_stdio(ChardevStdio
> *opts)
> chr = qemu_chr_open_fd(0, 1);
> chr->chr_close = qemu_chr_close_stdio;
> chr->chr_set_echo = qemu_chr_set_echo_stdio;
> - stdio_allow_signal = display_type != DT_NOGRAPHIC;
> if (opts->has_signal) {
> stdio_allow_signal = opts->signal;
> }
> @@ -2932,6 +2930,14 @@ QemuOpts *qemu_chr_parse_compat(const char *label,
> const char *filename)
> if (strstart(filename, "mon:", &p)) {
> filename = p;
> qemu_opt_set(opts, "mux", "on");
> + if (strcmp(filename, "stdio") == 0) {
> + /* Monitor is muxed to stdio: do not exit on Ctrl+C by default
> + * but pass it to the guest. Handle this only for compat syntax,
> + * for -chardev syntax we have special option for this.
> + * This is what -nographic did, redirecting+muxing serial+monitor
> + * to stdio causing Ctrl+C to be passed to guest. */
> + qemu_opt_set(opts, "signal", "off");
> + }
> }
>
> if (strcmp(filename, "null") == 0 ||
> @@ -3060,8 +3066,7 @@ static void qemu_chr_parse_stdio(QemuOpts *opts,
> ChardevBackend *backend,
> {
> backend->stdio = g_new0(ChardevStdio, 1);
> backend->stdio->has_signal = true;
> - backend->stdio->signal =
> - qemu_opt_get_bool(opts, "signal", display_type != DT_NOGRAPHIC);
> + backend->stdio->signal = qemu_opt_get_bool(opts, "signal", true);
> }
>
> static void qemu_chr_parse_serial(QemuOpts *opts, ChardevBackend *backend,
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 137a39b..d676b03 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -842,7 +842,8 @@ STEXI
> Normally, QEMU uses SDL to display the VGA output. With this option,
> you can totally disable graphical output so that QEMU is a simple
> command line application. The emulated serial port is redirected on
> -the console. Therefore, you can still use QEMU to debug a Linux kernel
> +the console and muxed with the monitor (unless redirected elsewhere
> +explicitly).
By default, the emulated serial port and the monitor are multiplexed on
the console; @option{-serial} and @option{-monitor} can be used to
change this default.
Therefore, you can still use QEMU to debug a Linux kernel
> with a serial console.
> ETEXI
>
> @@ -2485,14 +2486,15 @@ same as if you had specified @code{-serial tcp}
> except the unix domain socket
> @item mon:@var{dev_string}
> This is a special option to allow the monitor to be multiplexed onto
> another serial port. The monitor is accessed with key sequence of
> address@hidden and then pressing @key{c}. See monitor access
> address@hidden in the -nographic section for more keys.
> address@hidden and then pressing @key{c}.
> @var{dev_string} should be any one of the serial devices specified
> above. An example to multiplex the monitor onto a telnet server
> listening on port 4444 would be:
> @table @code
> @item -serial mon:telnet::4444,server,nowait
> @end table
> +When monitor is multiplexed to stdio this way, Ctrl+C will not terminate
> +guest anymore but will be passed to the guest as is.
will not terminate QEMU anymore...
>
> @item braille
> Braille device. This will use BrlAPI to display the braille output on a real
>
Also, there is another reference to -nographic here:
@item -echr @var{numeric_ascii_value}
@findex -echr
Change the escape character used for switching to the monitor when using
monitor and serial sharing. The default is @code{0x01} when using the
@code{-nographic} option. @code{0x01} is equal to pressing
@code{Control-a}. You can select a different character from the ascii
control keys where 1 through 26 map to Control-a through Control-z. For
instance you could use the either of the following to change the escape
character to Control-t.
You could remove "when using the @code{-nographic} option" from this
paragraph.
Paolo