powerpc: Export memory limit via device tree
The powerpc kernel doesn't export the memory limit enforced by 'mem=' kernel parameter. This is required for building the ELF header in kexec-tools to limit the vmcore to capture only the used memory. On powerpc the kexec-tools depends on the device-tree for memory related information, unlike /proc/iomem on the x86. Without this information, the kexec-tools assumes the entire System RAM and vmcore creates an unnecessarily larger dump. This patch exports the memory limit, if present, via chosen/linux,memory-limit property, so that the vmcore can be limited to the memory limit. The prom_init seems to export this value in the same node. But doesn't really appear there. Also the memory_limit gets adjusted with the processing of crashkernel= parameter. This patch makes sure we get the actual limit. The kexec-tools will use the value to limit the 'end' of the memory regions. Tested this patch on ppc64 and ppc32(ppc440) with a kexec-tools patch by Mahesh. Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com> Tested-by: Mahesh J. Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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@ -204,6 +204,12 @@ static struct property crashk_size_prop = {
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.value = &crashk_size,
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};
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static struct property memory_limit_prop = {
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.name = "linux,memory-limit",
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.length = sizeof(unsigned long long),
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.value = &memory_limit,
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};
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static void __init export_crashk_values(struct device_node *node)
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{
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struct property *prop;
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@ -223,6 +229,12 @@ static void __init export_crashk_values(struct device_node *node)
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crashk_size = resource_size(&crashk_res);
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prom_add_property(node, &crashk_size_prop);
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}
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/*
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* memory_limit is required by the kexec-tools to limit the
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* crash regions to the actual memory used.
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*/
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prom_update_property(node, &memory_limit_prop);
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}
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static int __init kexec_setup(void)
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