[PATCH 0/3] kdb: Delete never used KGDB NMI code

[PATCH 0/3] kdb: Delete never used KGDB NMI code

[Douglas Anderson]

As pointed out in the review [1] of commit 39d0be87438a ("serial:
kgdb_nmi: Remove unused knock code"), it's not just the knock code
that's unused but a whole chunk of NMI-related code in KGDB.

Look back at the original series [2] and revert a few of the patches
that managed to land and had no other purpose. They've been in the
kernel for over 12 years and if nobody has used them during that time
then they won't get used.

I've validated things still compile just fine for me and I've tested
"allmodconfig" for a few different architectures. Hopefully I didn't
miss anything, but based on "grep" this is all just dead code.

I guess I'd expect this to land through Greg KH's tree, ideally Acked
by Daniel Thompson.

[1] https://lore.kernel.org/r/CAD=FV=VH5YWfTggGNt2KLoSPKqVTmWArEgccok3uFQ5BCA7cNw@mail.gmail.com
[2] https://lore.kernel.org/lkml/1348522080-32629-9-git-send-email-anton.vorontsov@linaro.org/


Douglas Anderson (3):
  Revert "tty/serial: Add kgdb_nmi driver"
  Revert "kdb: Implement disable_nmi command"
  Revert "kernel/debug: Mask KGDB NMI upon entry"

 drivers/tty/serial/Kconfig    |  19 ---
 drivers/tty/serial/Makefile   |   1 -
 drivers/tty/serial/kgdb_nmi.c | 280 ----------------------------------
 drivers/tty/serial/kgdboc.c   |   8 -
 include/linux/kgdb.h          |  11 --
 kernel/debug/debug_core.c     |  14 +-
 kernel/debug/kdb/kdb_main.c   |  37 -----
 7 files changed, 3 insertions(+), 367 deletions(-)
 delete mode 100644 drivers/tty/serial/kgdb_nmi.c

-- 
2.48.1.262.g85cc9f2d1e-goog

[PATCH 1/3] Revert "tty/serial: Add kgdb_nmi driver"

[Douglas Anderson]

This reverts commit 0c57dfcc6c1d037243c2f8fbf62eab3633326ec0.

The functionality was supoosed to be used by a later patch in the
series that never landed [1]. Drop it.

NOTE: part of functionality was already reverted by commit
39d0be87438a ("serial: kgdb_nmi: Remove unused knock code"). Also note
that this revert is not a clean revert given code changes that have
happened in the meantime.

It's obvious that nobody is using this code since the two exposed
functions (kgdb_register_nmi_console() and
kgdb_unregister_nmi_console()) are both no-ops if
"arch_kgdb_ops.enable_nmi" is not defined. No architectures define it.

[1] https://lore.kernel.org/lkml/1348522080-32629-9-git-send-email-anton.vorontsov@linaro.org/

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 drivers/tty/serial/Kconfig    |  19 ---
 drivers/tty/serial/Makefile   |   1 -
 drivers/tty/serial/kgdb_nmi.c | 280 ----------------------------------
 drivers/tty/serial/kgdboc.c   |   8 -
 include/linux/kgdb.h          |   8 -
 5 files changed, 316 deletions(-)
 delete mode 100644 drivers/tty/serial/kgdb_nmi.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 976dae3bb1bb..f21cad6aaa47 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -179,25 +179,6 @@ config SERIAL_ATMEL_TTYAT
 
 	  Say Y if you have an external 8250/16C550 UART.  If unsure, say N.
 
-config SERIAL_KGDB_NMI
-	bool "Serial console over KGDB NMI debugger port"
-	depends on KGDB_SERIAL_CONSOLE
-	help
-	  This special driver allows you to temporary use NMI debugger port
-	  as a normal console (assuming that the port is attached to KGDB).
-
-	  Unlike KDB's disable_nmi command, with this driver you are always
-	  able to go back to the debugger using KGDB escape sequence ($3#33).
-	  This is because this console driver processes the input in NMI
-	  context, and thus is able to intercept the magic sequence.
-
-	  Note that since the console interprets input and uses polling
-	  communication methods, for things like PPP you still must fully
-	  detach debugger port from the KGDB NMI (i.e. disable_nmi), and
-	  use raw console.
-
-	  If unsure, say N.
-
 config SERIAL_MESON
 	tristate "Meson serial port support"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 6ff74f0a9530..3019260d9120 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -96,6 +96,5 @@ obj-$(CONFIG_SERIAL_ZS)			+= zs.o
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
 
-obj-$(CONFIG_SERIAL_KGDB_NMI) += kgdb_nmi.o
 obj-$(CONFIG_KGDB_SERIAL_CONSOLE) += kgdboc.o
 obj-$(CONFIG_SERIAL_NUVOTON_MA35D1) += ma35d1_serial.o
diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c
deleted file mode 100644
index 2833708e369f..000000000000
--- a/drivers/tty/serial/kgdb_nmi.c
+++ /dev/null
@@ -1,280 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * KGDB NMI serial console
- *
- * Copyright 2010 Google, Inc.
- *		  Arve Hjønnevåg <arve@android.com>
- *		  Colin Cross <ccross@android.com>
- * Copyright 2012 Linaro Ltd.
- *		  Anton Vorontsov <anton.vorontsov@linaro.org>
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/compiler.h>
-#include <linux/slab.h>
-#include <linux/errno.h>
-#include <linux/atomic.h>
-#include <linux/console.h>
-#include <linux/tty.h>
-#include <linux/tty_driver.h>
-#include <linux/tty_flip.h>
-#include <linux/serial_core.h>
-#include <linux/interrupt.h>
-#include <linux/hrtimer.h>
-#include <linux/tick.h>
-#include <linux/kfifo.h>
-#include <linux/kgdb.h>
-#include <linux/kdb.h>
-
-static atomic_t kgdb_nmi_num_readers = ATOMIC_INIT(0);
-
-static int kgdb_nmi_console_setup(struct console *co, char *options)
-{
-	arch_kgdb_ops.enable_nmi(1);
-
-	/* The NMI console uses the dbg_io_ops to issue console messages. To
-	 * avoid duplicate messages during kdb sessions we must inform kdb's
-	 * I/O utilities that messages sent to the console will automatically
-	 * be displayed on the dbg_io.
-	 */
-	dbg_io_ops->cons = co;
-
-	return 0;
-}
-
-static void kgdb_nmi_console_write(struct console *co, const char *s, uint c)
-{
-	int i;
-
-	for (i = 0; i < c; i++)
-		dbg_io_ops->write_char(s[i]);
-}
-
-static struct tty_driver *kgdb_nmi_tty_driver;
-
-static struct tty_driver *kgdb_nmi_console_device(struct console *co, int *idx)
-{
-	*idx = co->index;
-	return kgdb_nmi_tty_driver;
-}
-
-static struct console kgdb_nmi_console = {
-	.name	= "ttyNMI",
-	.setup  = kgdb_nmi_console_setup,
-	.write	= kgdb_nmi_console_write,
-	.device	= kgdb_nmi_console_device,
-	.flags	= CON_PRINTBUFFER | CON_ANYTIME,
-	.index	= -1,
-};
-
-/*
- * This is usually the maximum rate on debug ports. We make fifo large enough
- * to make copy-pasting to the terminal usable.
- */
-#define KGDB_NMI_BAUD		115200
-#define KGDB_NMI_FIFO_SIZE	roundup_pow_of_two(KGDB_NMI_BAUD / 8 / HZ)
-
-struct kgdb_nmi_tty_priv {
-	struct tty_port port;
-	struct timer_list timer;
-	STRUCT_KFIFO(char, KGDB_NMI_FIFO_SIZE) fifo;
-};
-
-static struct tty_port *kgdb_nmi_port;
-
-/*
- * The tasklet is cheap, it does not cause wakeups when reschedules itself,
- * instead it waits for the next tick.
- */
-static void kgdb_nmi_tty_receiver(struct timer_list *t)
-{
-	struct kgdb_nmi_tty_priv *priv = from_timer(priv, t, timer);
-	char ch;
-
-	priv->timer.expires = jiffies + (HZ/100);
-	add_timer(&priv->timer);
-
-	if (likely(!atomic_read(&kgdb_nmi_num_readers) ||
-		   !kfifo_len(&priv->fifo)))
-		return;
-
-	while (kfifo_out(&priv->fifo, &ch, 1))
-		tty_insert_flip_char(&priv->port, ch, TTY_NORMAL);
-	tty_flip_buffer_push(&priv->port);
-}
-
-static int kgdb_nmi_tty_activate(struct tty_port *port, struct tty_struct *tty)
-{
-	struct kgdb_nmi_tty_priv *priv =
-	    container_of(port, struct kgdb_nmi_tty_priv, port);
-
-	kgdb_nmi_port = port;
-	priv->timer.expires = jiffies + (HZ/100);
-	add_timer(&priv->timer);
-
-	return 0;
-}
-
-static void kgdb_nmi_tty_shutdown(struct tty_port *port)
-{
-	struct kgdb_nmi_tty_priv *priv =
-	    container_of(port, struct kgdb_nmi_tty_priv, port);
-
-	del_timer(&priv->timer);
-	kgdb_nmi_port = NULL;
-}
-
-static const struct tty_port_operations kgdb_nmi_tty_port_ops = {
-	.activate	= kgdb_nmi_tty_activate,
-	.shutdown	= kgdb_nmi_tty_shutdown,
-};
-
-static int kgdb_nmi_tty_install(struct tty_driver *drv, struct tty_struct *tty)
-{
-	struct kgdb_nmi_tty_priv *priv;
-	int ret;
-
-	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-	if (!priv)
-		return -ENOMEM;
-
-	INIT_KFIFO(priv->fifo);
-	timer_setup(&priv->timer, kgdb_nmi_tty_receiver, 0);
-	tty_port_init(&priv->port);
-	priv->port.ops = &kgdb_nmi_tty_port_ops;
-	tty->driver_data = priv;
-
-	ret = tty_port_install(&priv->port, drv, tty);
-	if (ret) {
-		pr_err("%s: can't install tty port: %d\n", __func__, ret);
-		goto err;
-	}
-	return 0;
-err:
-	tty_port_destroy(&priv->port);
-	kfree(priv);
-	return ret;
-}
-
-static void kgdb_nmi_tty_cleanup(struct tty_struct *tty)
-{
-	struct kgdb_nmi_tty_priv *priv = tty->driver_data;
-
-	tty->driver_data = NULL;
-	tty_port_destroy(&priv->port);
-	kfree(priv);
-}
-
-static int kgdb_nmi_tty_open(struct tty_struct *tty, struct file *file)
-{
-	struct kgdb_nmi_tty_priv *priv = tty->driver_data;
-	unsigned int mode = file->f_flags & O_ACCMODE;
-	int ret;
-
-	ret = tty_port_open(&priv->port, tty, file);
-	if (!ret && (mode == O_RDONLY || mode == O_RDWR))
-		atomic_inc(&kgdb_nmi_num_readers);
-
-	return ret;
-}
-
-static void kgdb_nmi_tty_close(struct tty_struct *tty, struct file *file)
-{
-	struct kgdb_nmi_tty_priv *priv = tty->driver_data;
-	unsigned int mode = file->f_flags & O_ACCMODE;
-
-	if (mode == O_RDONLY || mode == O_RDWR)
-		atomic_dec(&kgdb_nmi_num_readers);
-
-	tty_port_close(&priv->port, tty, file);
-}
-
-static void kgdb_nmi_tty_hangup(struct tty_struct *tty)
-{
-	struct kgdb_nmi_tty_priv *priv = tty->driver_data;
-
-	tty_port_hangup(&priv->port);
-}
-
-static unsigned int kgdb_nmi_tty_write_room(struct tty_struct *tty)
-{
-	/* Actually, we can handle any amount as we use polled writes. */
-	return 2048;
-}
-
-static ssize_t kgdb_nmi_tty_write(struct tty_struct *tty, const u8 *buf,
-				  size_t c)
-{
-	int i;
-
-	for (i = 0; i < c; i++)
-		dbg_io_ops->write_char(buf[i]);
-	return c;
-}
-
-static const struct tty_operations kgdb_nmi_tty_ops = {
-	.open		= kgdb_nmi_tty_open,
-	.close		= kgdb_nmi_tty_close,
-	.install	= kgdb_nmi_tty_install,
-	.cleanup	= kgdb_nmi_tty_cleanup,
-	.hangup		= kgdb_nmi_tty_hangup,
-	.write_room	= kgdb_nmi_tty_write_room,
-	.write		= kgdb_nmi_tty_write,
-};
-
-int kgdb_register_nmi_console(void)
-{
-	int ret;
-
-	if (!arch_kgdb_ops.enable_nmi)
-		return 0;
-
-	kgdb_nmi_tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW);
-	if (IS_ERR(kgdb_nmi_tty_driver)) {
-		pr_err("%s: cannot allocate tty\n", __func__);
-		return PTR_ERR(kgdb_nmi_tty_driver);
-	}
-	kgdb_nmi_tty_driver->driver_name	= "ttyNMI";
-	kgdb_nmi_tty_driver->name		= "ttyNMI";
-	kgdb_nmi_tty_driver->num		= 1;
-	kgdb_nmi_tty_driver->type		= TTY_DRIVER_TYPE_SERIAL;
-	kgdb_nmi_tty_driver->subtype		= SERIAL_TYPE_NORMAL;
-	kgdb_nmi_tty_driver->init_termios	= tty_std_termios;
-	tty_termios_encode_baud_rate(&kgdb_nmi_tty_driver->init_termios,
-				     KGDB_NMI_BAUD, KGDB_NMI_BAUD);
-	tty_set_operations(kgdb_nmi_tty_driver, &kgdb_nmi_tty_ops);
-
-	ret = tty_register_driver(kgdb_nmi_tty_driver);
-	if (ret) {
-		pr_err("%s: can't register tty driver: %d\n", __func__, ret);
-		goto err_drv_reg;
-	}
-
-	register_console(&kgdb_nmi_console);
-
-	return 0;
-err_drv_reg:
-	tty_driver_kref_put(kgdb_nmi_tty_driver);
-	return ret;
-}
-EXPORT_SYMBOL_GPL(kgdb_register_nmi_console);
-
-int kgdb_unregister_nmi_console(void)
-{
-	int ret;
-
-	if (!arch_kgdb_ops.enable_nmi)
-		return 0;
-	arch_kgdb_ops.enable_nmi(0);
-
-	ret = unregister_console(&kgdb_nmi_console);
-	if (ret)
-		return ret;
-
-	tty_unregister_driver(kgdb_nmi_tty_driver);
-	tty_driver_kref_put(kgdb_nmi_tty_driver);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(kgdb_unregister_nmi_console);
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 58ea1e1391ce..85f6c5a76e0f 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -186,8 +186,6 @@ static void cleanup_kgdboc(void)
 	if (configured != 1)
 		return;
 
-	if (kgdb_unregister_nmi_console())
-		return;
 	kgdboc_unregister_kbd();
 	kgdb_unregister_io_module(&kgdboc_io_ops);
 }
@@ -250,16 +248,10 @@ static int configure_kgdboc(void)
 	if (err)
 		goto noconfig;
 
-	err = kgdb_register_nmi_console();
-	if (err)
-		goto nmi_con_failed;
-
 	configured = 1;
 
 	return 0;
 
-nmi_con_failed:
-	kgdb_unregister_io_module(&kgdboc_io_ops);
 noconfig:
 	kgdboc_unregister_kbd();
 	configured = 0;
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 51ef131e66b7..14739952698b 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -306,14 +306,6 @@ extern const struct kgdb_arch		arch_kgdb_ops;
 
 extern unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs);
 
-#ifdef CONFIG_SERIAL_KGDB_NMI
-extern int kgdb_register_nmi_console(void);
-extern int kgdb_unregister_nmi_console(void);
-#else
-static inline int kgdb_register_nmi_console(void) { return 0; }
-static inline int kgdb_unregister_nmi_console(void) { return 0; }
-#endif
-
 extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern struct kgdb_io *dbg_io_ops;
-- 
2.48.1.262.g85cc9f2d1e-goog

[PATCH 2/3] Revert "kdb: Implement disable_nmi command"

[Douglas Anderson]

This reverts commit ad394f66fa57ae66014cb74f337e2820bac4c417.

No architectures ever implemented `enable_nmi` since the later patches
in the series adding it never landed. It's been a long time. Drop it.

NOTE: this is not a clean revert due to changes in the file in the
meantime.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 kernel/debug/kdb/kdb_main.c | 37 -------------------------------------
 1 file changed, 37 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 5f4be507d79f..3a5408b54570 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -25,7 +25,6 @@
 #include <linux/smp.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
-#include <linux/atomic.h>
 #include <linux/moduleparam.h>
 #include <linux/mm.h>
 #include <linux/init.h>
@@ -2119,32 +2118,6 @@ static int kdb_dmesg(int argc, const char **argv)
 	return 0;
 }
 #endif /* CONFIG_PRINTK */
-
-/* Make sure we balance enable/disable calls, must disable first. */
-static atomic_t kdb_nmi_disabled;
-
-static int kdb_disable_nmi(int argc, const char *argv[])
-{
-	if (atomic_read(&kdb_nmi_disabled))
-		return 0;
-	atomic_set(&kdb_nmi_disabled, 1);
-	arch_kgdb_ops.enable_nmi(0);
-	return 0;
-}
-
-static int kdb_param_enable_nmi(const char *val, const struct kernel_param *kp)
-{
-	if (!atomic_add_unless(&kdb_nmi_disabled, -1, 0))
-		return -EINVAL;
-	arch_kgdb_ops.enable_nmi(1);
-	return 0;
-}
-
-static const struct kernel_param_ops kdb_param_ops_enable_nmi = {
-	.set = kdb_param_enable_nmi,
-};
-module_param_cb(enable_nmi, &kdb_param_ops_enable_nmi, NULL, 0600);
-
 /*
  * kdb_cpu - This function implements the 'cpu' command.
  *	cpu	[<cpunum>]
@@ -2836,20 +2809,10 @@ static kdbtab_t maintab[] = {
 	},
 };
 
-static kdbtab_t nmicmd = {
-	.name = "disable_nmi",
-	.func = kdb_disable_nmi,
-	.usage = "",
-	.help = "Disable NMI entry to KDB",
-	.flags = KDB_ENABLE_ALWAYS_SAFE,
-};
-
 /* Initialize the kdb command table. */
 static void __init kdb_inittab(void)
 {
 	kdb_register_table(maintab, ARRAY_SIZE(maintab));
-	if (arch_kgdb_ops.enable_nmi)
-		kdb_register_table(&nmicmd, 1);
 }
 
 /* Execute any commands defined in kdb_cmds.  */
-- 
2.48.1.262.g85cc9f2d1e-goog

[PATCH 3/3] Revert "kernel/debug: Mask KGDB NMI upon entry"

[Douglas Anderson]

This reverts commit 5a14fead07bcf4e0acc877a8d9e1d1f40a441153.

No architectures ever implemented `enable_nmi` since the later patches
in the series adding it never landed. It's been a long time. Drop it.

NOTE: this is not a clean revert due to changes in the file in the
meantime.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 include/linux/kgdb.h      |  3 ---
 kernel/debug/debug_core.c | 14 +++-----------
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 14739952698b..5eebbe7a3545 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -257,7 +257,6 @@ extern void kgdb_arch_late(void);
  * hardware breakpoints.
  * @correct_hw_break: Allow an architecture to specify how to correct the
  * hardware debug registers.
- * @enable_nmi: Manage NMI-triggered entry to KGDB
  */
 struct kgdb_arch {
 	unsigned char		gdb_bpt_instr[BREAK_INSTR_SIZE];
@@ -270,8 +269,6 @@ struct kgdb_arch {
 	void	(*disable_hw_break)(struct pt_regs *regs);
 	void	(*remove_all_hw_break)(void);
 	void	(*correct_hw_break)(void);
-
-	void	(*enable_nmi)(bool on);
 };
 
 /**
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index ce1bb2301c06..0b9495187fba 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -837,10 +837,6 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 {
 	struct kgdb_state kgdb_var;
 	struct kgdb_state *ks = &kgdb_var;
-	int ret = 0;
-
-	if (arch_kgdb_ops.enable_nmi)
-		arch_kgdb_ops.enable_nmi(0);
 	/*
 	 * Avoid entering the debugger if we were triggered due to an oops
 	 * but panic_timeout indicates the system should automatically
@@ -858,15 +854,11 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	ks->linux_regs		= regs;
 
 	if (kgdb_reenter_check(ks))
-		goto out; /* Ouch, double exception ! */
+		return 0; /* Ouch, double exception ! */
 	if (kgdb_info[ks->cpu].enter_kgdb != 0)
-		goto out;
+		return 0;
 
-	ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
-out:
-	if (arch_kgdb_ops.enable_nmi)
-		arch_kgdb_ops.enable_nmi(1);
-	return ret;
+	return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
 }
 NOKPROBE_SYMBOL(kgdb_handle_exception);
 
-- 
2.48.1.262.g85cc9f2d1e-goog

Re: [PATCH 1/3] Revert "tty/serial: Add kgdb_nmi driver"

[Andy Shevchenko]

On Wed, Jan 29, 2025 at 08:25:50AM -0800, Douglas Anderson wrote:
> This reverts commit 0c57dfcc6c1d037243c2f8fbf62eab3633326ec0.
> 
> The functionality was supoosed to be used by a later patch in the
> series that never landed [1]. Drop it.
> 
> NOTE: part of functionality was already reverted by commit
> 39d0be87438a ("serial: kgdb_nmi: Remove unused knock code"). Also note
> that this revert is not a clean revert given code changes that have
> happened in the meantime.
> 
> It's obvious that nobody is using this code since the two exposed
> functions (kgdb_register_nmi_console() and
> kgdb_unregister_nmi_console()) are both no-ops if
> "arch_kgdb_ops.enable_nmi" is not defined. No architectures define it.

Fine with me.
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> [1] https://lore.kernel.org/lkml/1348522080-32629-9-git-send-email-anton.vorontsov@linaro.org/

It might be possible to use Link tag here in a form

Link: URL [1]


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 1/3] Revert "tty/serial: Add kgdb_nmi driver"

[Andy Shevchenko]

On Thu, Jan 30, 2025 at 10:27:29AM +0200, Andy Shevchenko wrote:
> On Wed, Jan 29, 2025 at 08:25:50AM -0800, Douglas Anderson wrote:

...

> > [1] https://lore.kernel.org/lkml/1348522080-32629-9-git-send-email-anton.vorontsov@linaro.org/
> 
> It might be possible to use Link tag here in a form
> 
> Link: URL [1]

Hmm... I'm not sure what this Link is supposed to mean. You might be forgotten
to update an URL to point out to the cover letter? (This is the link to patch 9
in the series and looks a bit unrelated).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 1/3] Revert "tty/serial: Add kgdb_nmi driver"

[Andy Shevchenko]

On Thu, Jan 30, 2025 at 10:32:33AM +0200, Andy Shevchenko wrote:
> On Thu, Jan 30, 2025 at 10:27:29AM +0200, Andy Shevchenko wrote:
> > On Wed, Jan 29, 2025 at 08:25:50AM -0800, Douglas Anderson wrote:

...

> > > [1] https://lore.kernel.org/lkml/1348522080-32629-9-git-send-email-anton.vorontsov@linaro.org/
> > 
> > It might be possible to use Link tag here in a form
> > 
> > Link: URL [1]
> 
> Hmm... I'm not sure what this Link is supposed to mean. You might be forgotten
> to update an URL to point out to the cover letter? (This is the link to patch 9
> in the series and looks a bit unrelated).

I reread and I think now understand what you meant. The are several patches
starting from this one that are not landed in the upstream.

-- 
With Best Regards,
Andy Shevchenko