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 <nyushchenko at 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
