When preparing dump-capturing kernel, kexec userspace tool needs to know
actual amount of memory used by the running kernel. This may differ from
extire available DRAM for a couple of reasons. To address this issue,
kdump kernel support code injects several attributes into device tree that
are later captured by userspace kexec tool via /proc interface.
One such attrubute is 'chosen/linux,memory_limit' that is used to pass
memory limit of the running kernel.
This was initialized using kernel's 'memory_limit' variable, that is set
by early init code based on mem= kernel parameter and other reasons.
But there are cases when memory_limit variable does not contain proper
information. One such case is when !CONFIG_HIGHMEM kernel runs on system
with memory large enough not to fit into lowmem.
This patch fixes initialization of 'chosen/linux,memory_limit' to use
values from memblock subsystem. These are adjusted at kernel memory
management init and thus always contain values that match reality.
Signed-off-by: Nikita Yushchenko <nyushche...@dev.rtsoft.ru>
---
arch/powerpc/kernel/machine_kexec.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/machine_kexec.c
b/arch/powerpc/kernel/machine_kexec.c
index 015ae55..372cda5 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -250,8 +250,14 @@ static void __init export_crashk_values(struct device_node
*node)
/*
* memory_limit is required by the kexec-tools to limit the
* crash regions to the actual memory used.
+ *
+ * There are cases when memory_limit variable does not hold actual
+ * limit, for example when memory was limited by no kernel support
+ * for HIGHMEM. Reliable information is known by memblock because
+ * memory management init adjusts it.
*/
- mem_limit = cpu_to_be_ulong(memory_limit);
+ mem_limit = cpu_to_be_ulong(memblock_end_of_DRAM() -
+ memblock_start_of_DRAM());
of_update_property(node, &memory_limit_prop);
}
--
1.7.10.4
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