From f00ec48fadf5e37e7889f14cff900aa70d18b644 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 4 Sep 2010 10:47:48 +0100 Subject: ARM: Allow SMP kernels to boot on UP systems UP systems do not implement all the instructions that SMP systems have, so in order to boot a SMP kernel on a UP system, we need to rewrite parts of the kernel. Do this using an 'alternatives' scheme, where the kernel code and data is modified prior to initialization to replace the SMP instructions, thereby rendering the problematical code ineffectual. We use the linker to generate a list of 32-bit word locations and their replacement values, and run through these replacements when we detect a UP system. Signed-off-by: Russell King --- arch/arm/Kconfig | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/arm/Kconfig') diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 6a939e64cbd..f6cdc21b562 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1191,6 +1191,19 @@ config SMP If you don't know what to do here, say N. +config SMP_ON_UP + bool "Allow booting SMP kernel on uniprocessor systems (EXPERIMENTAL)" + depends on EXPERIMENTAL + depends on SMP && !XIP && !THUMB2_KERNEL + default y + help + SMP kernels contain instructions which fail on non-SMP processors. + Enabling this option allows the kernel to modify itself to make + these instructions safe. Disabling it allows about 1K of space + savings. + + If you don't know what to do here, say Y. + config HAVE_ARM_SCU bool depends on SMP -- cgit v1.2.3-70-g09d2