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Subject[RFC PATCH] memory-hotplug: add sysfs immovable_mem attribute
Date
In sometimes users specify the memory region in immovable node in
some kernel commandline, such as "kernel_core" or the "immovable_mem="
in the patchset that I have send. But users don't know the memory
region. So add this interface to print it.

It will show like this: "nn@ss,nn@ss,...". "nn" means the size of memory
region, "ss" means the start position of this region.

Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
---
drivers/base/memory.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 1d60b58a8c19..9cadf1a9dccb 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -25,6 +25,7 @@

#include <linux/atomic.h>
#include <linux/uaccess.h>
+#include <linux/acpi.h>

static DEFINE_MUTEX(mem_sysfs_mutex);

@@ -389,6 +390,52 @@ static ssize_t show_phys_device(struct device *dev,
}

#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * Immovable memory region
+ */
+
+static ssize_t
+show_immovable_mem(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct acpi_table_header *table_header = NULL;
+ struct acpi_srat_mem_affinity *ma;
+ struct acpi_subtable_header *th;
+ unsigned long long table_size;
+ unsigned long long table_end;
+ char pbuf[35], *p = buf;
+ int len;
+
+ acpi_get_table(ACPI_SIG_SRAT, 0, &table_header);
+
+ table_size = sizeof(struct acpi_table_srat);
+ table_end = (unsigned long)table_header + table_header->length;
+ th = (struct acpi_subtable_header *)((unsigned long)
+ table_header + table_size);
+
+ while (((unsigned long)th) +
+ sizeof(struct acpi_subtable_header) < table_end) {
+ if (th->type == 1) {
+ ma = (struct acpi_srat_mem_affinity *)th;
+ if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE)
+ continue;
+ len = sprintf(pbuf, "%llx@%llx",
+ ma->length, ma->base_address);
+ if (p != buf) {
+ *p = ',';
+ p++;
+ }
+ memcpy(p, pbuf, len);
+ p = p + len;
+ }
+ th = (struct acpi_subtable_header *)((unsigned long)
+ th + th->length);
+ }
+ return sprintf(buf, "%s\n", buf);
+}
+
+static DEVICE_ATTR(immovable_mem, 0444, show_immovable_mem, NULL);
+
static void print_allowed_zone(char *buf, int nid, unsigned long start_pfn,
unsigned long nr_pages, int online_type,
struct zone *default_zone)
@@ -798,6 +845,9 @@ static struct attribute *memory_root_attrs[] = {
#endif

&dev_attr_block_size_bytes.attr,
+#ifdef CONFIG_MEMORY_HOTREMOVE
+ &dev_attr_immovable_mem.attr,
+#endif
&dev_attr_auto_online_blocks.attr,
NULL
};
--
2.14.3


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