From: Suzuki Poulose Date: Tue, 21 Aug 2012 01:42:43 +0000 (+0000) Subject: powerpc: Export memory limit via device tree X-Git-Tag: firefly_0821_release~3680^2~1912^2~75 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4bc77a5ed215b4ec9cc39d5f55323b2e68000055;p=firefly-linux-kernel-4.4.55.git 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 Tested-by: Mahesh J. Salgaonkar Signed-off-by: Benjamin Herrenschmidt --- diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c index 4074eff1e744..fa9f6c72f557 100644 --- a/arch/powerpc/kernel/machine_kexec.c +++ b/arch/powerpc/kernel/machine_kexec.c @@ -204,6 +204,12 @@ static struct property crashk_size_prop = { .value = &crashk_size, }; +static struct property memory_limit_prop = { + .name = "linux,memory-limit", + .length = sizeof(unsigned long long), + .value = &memory_limit, +}; + static void __init export_crashk_values(struct device_node *node) { struct property *prop; @@ -223,6 +229,12 @@ static void __init export_crashk_values(struct device_node *node) crashk_size = resource_size(&crashk_res); prom_add_property(node, &crashk_size_prop); } + + /* + * memory_limit is required by the kexec-tools to limit the + * crash regions to the actual memory used. + */ + prom_update_property(node, &memory_limit_prop); } static int __init kexec_setup(void)