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ARM: 7073/1: debug: augment DEBUG_LL Kconfig help to clarify behaviour
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Enabled DEBUG_LL hardcodes the UART address into the kernel and results
in a non-portable kernel image. Since this option is only intended for
use when debugging early boot failures, supporting multiple platforms
in such a configuration is not the intended use-case.

This patch documents this limitation in the DEBUG_LL Kconfig help text,
so that users are aware of the portability restrictions that are associated
with enabling low-level debugging support.

Reported-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Will Deacon authored and Russell King committed Oct 17, 2011
1 parent 17916b2 commit 4f5ef92
Showing 1 changed file with 6 additions and 1 deletion.
7 changes: 6 additions & 1 deletion arch/arm/Kconfig.debug
Original file line number Diff line number Diff line change
Expand Up @@ -65,13 +65,18 @@ config DEBUG_USER

# These options are only for real kernel hackers who want to get their hands dirty.
config DEBUG_LL
bool "Kernel low-level debugging functions"
bool "Kernel low-level debugging functions (read help!)"
depends on DEBUG_KERNEL
help
Say Y here to include definitions of printascii, printch, printhex
in the kernel. This is helpful if you are debugging code that
executes before the console is initialized.

Note that selecting this option will limit the kernel to a single
UART definition, as specified below. Attempting to boot the kernel
image on a different platform *will not work*, so this option should
not be enabled for kernels that are intended to be portable.

choice
prompt "Kernel low-level debugging port"
depends on DEBUG_LL
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