diff mbox series

[1/2] ttynull: Add an option to allow ttynull to be used as a console device

Message ID 20241129041549.778959-2-bluescreen_avenger@verizon.net
State New
Headers show
Series Optionally allow ttynull to be selected as a default console | expand

Commit Message

n3rdopolis Nov. 29, 2024, 4:15 a.m. UTC
Add a config option CONFIG_NULL_TTY_CONSOLE that will have ttynull be
initialized by console_initcall() and selected as a possible console
device.
Signed-off-by: n3rdopolis <bluescreen_avenger@verizon.net>
---
 drivers/tty/Kconfig   | 18 +++++++++++++++++-
 drivers/tty/ttynull.c | 16 +++++++++++++++-
 2 files changed, 32 insertions(+), 2 deletions(-)

Comments

Greg KH Dec. 4, 2024, 3:41 p.m. UTC | #1
On Thu, Nov 28, 2024 at 11:15:48PM -0500, n3rdopolis wrote:
> Add a config option CONFIG_NULL_TTY_CONSOLE that will have ttynull be
> initialized by console_initcall() and selected as a possible console
> device.
> Signed-off-by: n3rdopolis <bluescreen_avenger@verizon.net>

Meta-comments, we need a blank line before the s-o-b line, AND we need a
real name here, sorry.  I can't do anything with these (including
reviewing them), until that happens.

thanks,

greg k-h
Greg KH Dec. 4, 2024, 6:06 p.m. UTC | #2
On Wed, Dec 04, 2024 at 12:06:56PM -0500, n3rdopolis wrote:
> On Wednesday, December 4, 2024 10:41:44 AM EST Greg Kroah-Hartman wrote:
> > On Thu, Nov 28, 2024 at 11:15:48PM -0500, n3rdopolis wrote:
> > > Add a config option CONFIG_NULL_TTY_CONSOLE that will have ttynull be
> > > initialized by console_initcall() and selected as a possible console
> > > device.
> > > Signed-off-by: n3rdopolis <bluescreen_avenger@verizon.net>
> > 
> > Meta-comments, we need a blank line before the s-o-b line, AND we need a
> > real name here, sorry.  I can't do anything with these (including
> > reviewing them), until that happens.
> > 
> Oh, I thought that I didn't need a real name
> 
> I found a recent thread that seems like it suggests that I thought
> https://lore.kernel.org/all/20241121165806.476008-40-alex.bennee@linaro.org/[1]
> https://drewdevault.com/2023/10/31/On-real-names.html[2]
> Or do I need to wait for that change to the guideline be merged?

That change has been merged a long time ago, but as far as I can tell,
this signed-off-by you used here does not meet this category.

thanks,

greg k-h
diff mbox series

Patch

diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index 63a494d36a1f..afe4e7722d4c 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -383,7 +383,23 @@  config NULL_TTY
 	  available or desired.
 
 	  In order to use this driver, you should redirect the console to this
-	  TTY, or boot the kernel with console=ttynull.
+	  TTY, boot the kernel with console=ttynull, or enable
+	  CONFIG_NULL_TTY_CONSOLE.
+
+	  If unsure, say N.
+
+config NULL_TTY_CONSOLE
+        bool "Supports /dev/ttynull as a console automatically"
+        depends on NULL_TTY=y && !VT_CONSOLE
+	help
+	  Say Y here if you want the NULL TTY to be used as a /dev/console
+	  device.
+
+	  This is useful for userspace applications that expect a working
+	  console device, without changing the kernel boot options, such as a
+	  distribuition or environment that historically had CONFIG_VT_CONSOLE
+	  enabled, and have now disabled it, but still need /dev/console to be
+	  working for userspace applications.
 
 	  If unsure, say N.
 
diff --git a/drivers/tty/ttynull.c b/drivers/tty/ttynull.c
index 6b2f7208b564..8ba629ae426b 100644
--- a/drivers/tty/ttynull.c
+++ b/drivers/tty/ttynull.c
@@ -57,6 +57,10 @@  static struct tty_driver *ttynull_device(struct console *c, int *index)
 static struct console ttynull_console = {
 	.name = "ttynull",
 	.device = ttynull_device,
+#ifdef CONFIG_NULL_TTY_CONSOLE
+	.index = -1,
+	.flags = CON_PRINTBUFFER,
+#endif
 };
 
 static int __init ttynull_init(void)
@@ -90,10 +94,20 @@  static int __init ttynull_init(void)
 	}
 
 	ttynull_driver = driver;
-	register_console(&ttynull_console);
+	if (!console_is_registered(&ttynull_console))
+		register_console(&ttynull_console);
+
+	return 0;
+}
 
+#ifdef CONFIG_NULL_TTY_CONSOLE
+static int __init ttynull_register(void)
+{
+	register_console(&ttynull_console);
 	return 0;
 }
+console_initcall(ttynull_register);
+#endif
 
 static void __exit ttynull_exit(void)
 {