/etc/rc.sysinit script #'ing the lines out of /etc/inittab won't work
as it ignores the '#' and tries to access them anyway.
-Every Xenolinux instance owns a bidirectional 'virtual
-console'. Boot-time output will be directed to this console by default
-for all domain other than 0 (because the console name is tty0); domain
-0 requires you to specify 'console=xencons0' as a boot parameter. It
-is also possible to log in via the virtual console --- once again, for
-most domains your normal startup scripts will work as normal (e.g., by
-running mingetty on tty1-7). For domain 0, you must connect to the
-special 'xencons' device node:
- # mkdir -p /dev/xen
- # mknod /dev/xen/cons c 4 123
- # echo "c:2345:respawn:/sbin/mingetty --noclear xen/cons" >>/etc/inittab
-If you wish to permit root logins via the special DOM0 node then you
-must also add 'xen/cons' to the list of trusted ttys in
-/etc/securetty.
+Every Xenolinux instance owns a bidirectional 'virtual console'.
+The device node to which this console is attached can be configured
+by specifying 'xencons=' on the OS command line:
+ 'xencons=off' --> disable virtual console
+ 'xencons=tty' --> attach console to /dev/tty1 (tty0 at boot-time)
+ 'xencons=ttyS' --> attach console to /dev/ttyS0
+The default is to attach to /dev/tty1, and also to create dummy
+devices for /dev/tty2-63 to avoid warnings from many standard distro
+startup scripts. The exception is domain 0, which by default attaches
+to /dev/ttyS0.
Note that, because domains>0 don't have any privileged access at all,
certain commands in the default boot sequence will fail e.g. attempts
New console I/O infrastructure in Xen 1.3
=========================================
- Keir Fraser, University of Cambridge, 22nd March 2004
+ Keir Fraser, University of Cambridge, 3rd June 2004
I thought I'd write a quick note about using the new console I/O
infrastructure in Xen 1.3. Significant new features compared with 1.2,
- a new terminal client (replaces the use of telnet in character mode)
- proper handling of terminal emulation
+Accessing the virtual console from within the guest OS
+------------------------------------------------------
+ Every Xenolinux instance owns a bidirectional 'virtual console'.
+ The device node to which this console is attached can be configured
+ by specifying 'xencons=' on the OS command line:
+ 'xencons=off' --> disable virtual console
+ 'xencons=tty' --> attach console to /dev/tty1 (tty0 at boot-time)
+ 'xencons=ttyS' --> attach console to /dev/ttyS0
+ The default is to attach to /dev/tty1, and also to create dummy
+ devices for /dev/tty2-63 to avoid warnings from many standard distro
+ startup scripts. The exception is domain 0, which by default attaches
+ to /dev/ttyS0.
+
Domain 0 virtual console
------------------------
The virtual console for domain 0 is shared with Xen's console. For
example, if you specify 'console=com1' as a boot parameter to Xen,
then domain 0 will have bi-directional access to the primary serial
line. Boot-time messages can be directed to the virtual console by
- specifying 'console=xencons0' as a boot parameter to Xenolinux.
+ specifying 'console=ttyS0' as a boot parameter to Xenolinux.
Connecting to the virtual console
---------------------------------
'getty' is running. In most domains the virtual console is named tty1
so standard startup scripts and /etc/inittab should work
fine. Furthermore, tty2-63 are created as dummy console devices to
- suppress warnings from standard startup scripts.
-
- In domain 0 we avoid conflict with the 'real' console by registering
- the virtual console with a special device number. A suitable device
- node must therefore be created, and a new line added to inittab:
- # mkdir -p /dev/xen
- # mknod /dev/xen/cons c 4 123
- # echo "c:2345:respawn:/sbin/mingetty --noclear xen/cons" >>/etc/inittab
- Additionally, if you wish to allow root logins via the virtual
- console, then 'xen/cons' must be added to the trusted tty list in
- /etc/securetty. On some systems you *may* also need to modify the
- file /etc/securettys (note the final 's').
+ suppress warnings from standard startup scripts. If the OS has
+ attached the virtual console to /dev/ttyS0 then you will need to
+ start a 'mingetty' on that device node.
Virtual console for other domains
---------------------------------
Boot-time output will be directed to this console by default, because
the console name is tty0. It is also possible to log in via the
virtual console --- once again, your normal startup scripts will work
-as normal (e.g., by running mingetty on tty1-7).
+as normal (e.g., by running mingetty on tty1-7). The device node to
+which the virtual console is attached can be configured by specifying
+'xencons=' on the OS command line:
+ 'xencons=off' --> disable virtual console
+ 'xencons=tty' --> attach console to /dev/tty1 (tty0 at boot-time)
+ 'xencons=ttyS' --> attach console to /dev/ttyS0
Manage Running Domains
#include <asm/ctrl_if.h>
/*
- * NB. /dev/xencons[0-9]+ are only exported by domain 0.
- * All other domains use the normal /dev/tty[0-9]+ device nodes.
- * Only /dev/tty1 is currently hooked up to real I/O -- all others are
- * dummies to suppress warnings from standard distro startip scripts.
+ * Modes:
+ * 'xencons=off' [XC_OFF]: Console is disabled.
+ * 'xencons=tty' [XC_TTY]: Console attached to '/dev/tty[0-9]+'.
+ * 'xencons=ttyS' [XC_SERIAL]: Console attached to '/dev/ttyS[0-9]+'.
+ * [XC_DEFAULT]: DOM0 -> XC_SERIAL ; all others -> XC_TTY.
+ *
+ * NB. In mode XC_TTY, we create dummy consoles for tty2-63. This suppresses
+ * warnings from standard distro startup scripts.
*/
-#define XENCONS_TTY_MINOR 123
+static enum { XC_OFF, XC_DEFAULT, XC_TTY, XC_SERIAL } xc_mode = XC_DEFAULT;
+
+static int __init xencons_setup(char *str)
+{
+ if ( !strcmp(str, "tty") )
+ xc_mode = XC_TTY;
+ else if ( !strcmp(str, "ttyS") )
+ xc_mode = XC_SERIAL;
+ else if ( !strcmp(str, "off") )
+ xc_mode = XC_OFF;
+ return 1;
+}
+__setup("xencons", xencons_setup);
/* The kernel and user-land drivers share a common transmit buffer. */
#define WBUF_SIZE 4096
static kdev_t kcons_device(struct console *c)
{
- return MKDEV(TTY_MAJOR, 1);
-}
-
-static kdev_t kcons_device_dom0(struct console *c)
-{
- return MKDEV(TTY_MAJOR, XENCONS_TTY_MINOR);
+ return MKDEV(TTY_MAJOR, (xc_mode == XC_SERIAL) ? 64 : 1);
}
static struct console kcons_info = {
+ device: kcons_device,
flags: CON_PRINTBUFFER,
- index: -1,
+ index: -1
};
void xen_console_init(void)
{
if ( start_info.flags & SIF_INITDOMAIN )
{
- strcpy(kcons_info.name, "xencons");
- kcons_info.device = kcons_device_dom0;
- kcons_info.write = kcons_write_dom0;
+ if ( xc_mode == XC_DEFAULT )
+ xc_mode = XC_SERIAL;
+ kcons_info.write = kcons_write_dom0;
}
else
{
- strcpy(kcons_info.name, "tty");
- kcons_info.device = kcons_device;
- kcons_info.write = kcons_write;
+ if ( xc_mode == XC_DEFAULT )
+ xc_mode = XC_TTY;
+ kcons_info.write = kcons_write;
}
- kcons_info.write =
- (start_info.flags & SIF_INITDOMAIN) ? kcons_write_dom0 : kcons_write;
+ if ( xc_mode == XC_OFF )
+ return;
+
+ if ( xc_mode == XC_SERIAL )
+ strcpy(kcons_info.name, "ttyS");
+ else
+ strcpy(kcons_info.name, "tty");
+
register_console(&kcons_info);
}
memset(&xencons_driver, 0, sizeof(struct tty_driver));
xencons_driver.magic = TTY_DRIVER_MAGIC;
xencons_driver.major = TTY_MAJOR;
- xencons_driver.num = MAX_NR_CONSOLES;
xencons_driver.type = TTY_DRIVER_TYPE_SERIAL;
xencons_driver.subtype = SERIAL_TYPE_NORMAL;
xencons_driver.init_termios = tty_std_termios;
xencons_driver.termios = xencons_termios;
xencons_driver.termios_locked = xencons_termios_locked;
- if ( start_info.flags & SIF_INITDOMAIN )
+ if ( xc_mode == XC_OFF )
+ return 0;
+
+ if ( xc_mode == XC_SERIAL )
{
- xencons_driver.name = "xencons";
- xencons_driver.minor_start = XENCONS_TTY_MINOR;
+ xencons_driver.name = "ttyS";
+ xencons_driver.minor_start = 64;
+ xencons_driver.num = 1;
}
else
{
xencons_driver.name = "tty";
xencons_driver.minor_start = 1;
+ xencons_driver.num = MAX_NR_CONSOLES;
}
xencons_driver.open = xencons_open;
projects / xen.git / commitdiff