diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0107-printk-add-console-handover.patch | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/debian/patches-rt/0107-printk-add-console-handover.patch b/debian/patches-rt/0107-printk-add-console-handover.patch new file mode 100644 index 000000000..9abc4efd5 --- /dev/null +++ b/debian/patches-rt/0107-printk-add-console-handover.patch @@ -0,0 +1,76 @@ +From ead093d95a7917fa12f9d4653032eac383d21c1d Mon Sep 17 00:00:00 2001 +From: John Ogness <john.ogness@linutronix.de> +Date: Mon, 30 Nov 2020 01:42:09 +0106 +Subject: [PATCH 107/323] printk: add console handover +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz + +If earlyprintk is used, a boot console will print directly to the +console immediately. The boot console will unregister itself as soon +as a non-boot console registers. However, the non-boot console does +not begin printing until its kthread has started. Since this happens +much later, there is a long pause in the console output. If the +ringbuffer is small, messages could even be dropped during the +pause. + +Add a new CON_HANDOVER console flag to be used internally by printk +in order to track which non-boot console took over from a boot +console. If handover consoles have implemented write_atomic(), they +are allowed to print directly to the console until their kthread can +take over. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + include/linux/console.h | 1 + + kernel/printk/printk.c | 8 +++++++- + 2 files changed, 8 insertions(+), 1 deletion(-) + +diff --git a/include/linux/console.h b/include/linux/console.h +index 3e99359e0660..027278792eea 100644 +--- a/include/linux/console.h ++++ b/include/linux/console.h +@@ -138,6 +138,7 @@ static inline int con_debug_leave(void) + #define CON_ANYTIME (16) /* Safe to call when cpu is offline */ + #define CON_BRL (32) /* Used for a braille device */ + #define CON_EXTENDED (64) /* Use the extended output format a la /dev/kmsg */ ++#define CON_HANDOVER (128) /* Device was previously a boot console. */ + + struct console { + char name[16]; +diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c +index 2b110b9ae34a..58da007d7c99 100644 +--- a/kernel/printk/printk.c ++++ b/kernel/printk/printk.c +@@ -1729,6 +1729,8 @@ static bool console_can_sync(struct console *con) + return false; + if (con->write_atomic && kernel_sync_mode()) + return true; ++ if (con->write_atomic && (con->flags & CON_HANDOVER) && !con->thread) ++ return true; + if (con->write && (con->flags & CON_BOOT) && !con->thread) + return true; + return false; +@@ -1740,6 +1742,8 @@ static bool call_sync_console_driver(struct console *con, const char *text, size + return false; + if (con->write_atomic && kernel_sync_mode()) + con->write_atomic(con, text, text_len); ++ else if (con->write_atomic && (con->flags & CON_HANDOVER) && !con->thread) ++ con->write_atomic(con, text, text_len); + else if (con->write && (con->flags & CON_BOOT) && !con->thread) + con->write(con, text, text_len); + else +@@ -2832,8 +2836,10 @@ void register_console(struct console *newcon) + * the real console are the same physical device, it's annoying to + * see the beginning boot messages twice + */ +- if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) ++ if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { + newcon->flags &= ~CON_PRINTBUFFER; ++ newcon->flags |= CON_HANDOVER; ++ } + + /* + * Put this console in the list - keep the +-- +2.43.0 + |