kernel: do not accept sysrq characters via serial port

many boards have a disconnected TTL level serial which can generate
some garbage that can lead to spurious false sysrq detects.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Backport of r37210

SVN-Revision: 38863

diff --git a/target/linux/generic/config-3.3 b/target/linux/generic/config-3.3
index 4f18587ca95c2ed7b25f70018d27b366588461b5..8f2f437bc0a5060e14f69c0c74eaab7aedc84f84 100644 (file)
--- a/target/linux/generic/config-3.3
+++ b/target/linux/generic/config-3.3
@@ -2576,6 +2576,7 @@ CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_NR_UARTS=2
 # CONFIG_SERIAL_8250_PCI is not set
 CONFIG_SERIAL_8250_RUNTIME_UARTS=2
+# CONFIG_SERIAL_8250_SYSRQ is not set
 # CONFIG_SERIAL_ALTERA_JTAGUART is not set
 # CONFIG_SERIAL_ALTERA_UART is not set
 CONFIG_SERIAL_CORE=y

diff --git a/target/linux/generic/patches-3.3/890-8250_optional_sysrq.patch b/target/linux/generic/patches-3.3/890-8250_optional_sysrq.patch
new file mode 100644 (file)
index 0000000..414e18e
--- /dev/null
+++ b/target/linux/generic/patches-3.3/890-8250_optional_sysrq.patch
@@ -0,0 +1,24 @@
+--- a/drivers/tty/serial/8250/8250.c
++++ b/drivers/tty/serial/8250/8250.c
+@@ -16,7 +16,7 @@
+  *  membase is an 'ioremapped' cookie.
+  */
+ 
+-#if defined(CONFIG_SERIAL_8250_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
++#if defined(CONFIG_SERIAL_8250_SYSRQ) && defined(CONFIG_MAGIC_SYSRQ)
+ #define SUPPORT_SYSRQ
+ #endif
+ 
+--- a/drivers/tty/serial/8250/Kconfig
++++ b/drivers/tty/serial/8250/Kconfig
+@@ -66,6 +66,10 @@ config SERIAL_8250_CONSOLE
+ 
+         If unsure, say N.
+ 
++config SERIAL_8250_SYSRQ
++      bool "Magic sysrq support on 8250/16550 devices"
++      depends on SERIAL_8250_CONSOLE
++
+ config FIX_EARLYCON_MEM
+       bool
+       depends on X86