Re: [Linux-kernel] [PATCH] ARM: kernel: respect device tree status of cpu nodes
From: Ben Dooks
Date: Thu Mar 06 2014 - 05:00:30 EST
On 05/03/14 20:33, Stephen Boyd wrote:
+Lorenzo
On 02/24/14 03:22, JÃrg Billeter wrote:
Skip 'disabled' cpu nodes when building the cpu logical map. This avoids
booting cpus that have been disabled in the device tree.
Signed-off-by: JÃrg Billeter <j@xxxxxxxxx>
Reviewed-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx>
---
arch/arm/kernel/devtree.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index 739c3df..9aed299 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -95,6 +95,10 @@ void __init arm_dt_init_cpu_maps(void)
if (of_node_cmp(cpu->type, "cpu"))
continue;
+ /* Check if CPU is enabled */
+ if (!of_device_is_available(cpu))
+ continue;
+
pr_debug(" * %s...\n", cpu->full_name);
/*
* A device tree containing CPU nodes with missing "reg"
This doesn't follow the ePAPR spec. According to ePAPR status="disabled"
in a cpu node means "the cpu is in a quiescent state" and one can enable
it by using the "enable-method". At the least, we should document this
in bindings/arm/cpus.txt if we can all agree that we want this
definition of disabled.
My view was that disabled should be the same as for the device case
as it makes sense that way.
We have a position where we want to use the .dtsi files but not all
cpus are available to the Linux. If we cannot use disabled then we
need some other method to say this cpu node is not available, so
please do not try and bring it online (saves boot time waiting for
CPU nodes that cannot online)
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
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