[PATCH] ARM: debug: provide dummy default option for DEBUG_LL UART choice

Will Deacon will.deacon at arm.com
Fri Sep 30 05:28:47 EDT 2011

Defaulting to DEBUG_ICEDCC will cause systems to hang during boot unless
a hardware debugger is listening to the debug comms. channel.

This patch adds a dummy UART option as the default DEBUG_LL choice which
requires the platform to do the right thing.

Acked-by: Stephen Boyd <sboyd at codeaurora.org>
Signed-off-by: Will Deacon <will.deacon at arm.com>

This came out of discussion on the list yesterday but I thought I'd better
post a patch before sending to Russell.


 arch/arm/Kconfig.debug |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 32b1be4..5bc7814 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -81,6 +81,14 @@ choice
 	prompt "Kernel low-level debugging port"
 	depends on DEBUG_LL
+		bool "No low-level debugging UART"
+		help
+		  Say Y here if your platform doesn't provide a UART option
+		  below. This relies on your platform choosing the right UART
+		  definition internally in order for low-level debugging to
+		  work.
 		bool "Kernel low-level debugging via EmbeddedICE DCC channel"
@@ -89,8 +97,8 @@ choice
 		  co-processor 14. This is known to work on the ARM9 style ICE
 		  channel and on the XScale with the PEEDI.
-		  It does include a timeout to ensure that the system does not
-		  totally freeze when there is nothing connected to read.
+		  Note that the system will appear to hang during boot if there
+		  is nothing connected to read from the DCC.
 		bool "Kernel low-level debugging messages via footbridge 8250 at PCI COM1"

More information about the linux-arm-kernel mailing list