---

yaml
---
r: 356255
b: refs/heads/master
c: 0212f91
h: refs/heads/master
i:
  356253: c610cd7
  356251: aa5e728
  356247: 59752bf
  356239: 884fc40
  356223: 0741e65
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7d41a8a4a2b2438621a9159477bff36a11d79a42
+refs/heads/master: 0212f9159694be61c6bc52e925fa76643e0c1abf

trunk/Documentation/kernel-parameters.txt

@@ -594,6 +594,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			is selected automatically. Check
 			Documentation/kdump/kdump.txt for further details.
 
+	crashkernel_low=size[KMG]
+			[KNL, x86] parts under 4G.
+
 	crashkernel=range1:size1[,range2:size2,...][@offset]
 			[KNL] Same as above, but depends on the memory
 			in the running system. The syntax of range is

trunk/arch/x86/kernel/setup.c

@@ -508,8 +508,44 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 # define CRASH_KERNEL_ADDR_MAX	MAXMEM
 #endif
 
+static void __init reserve_crashkernel_low(void)
+{
+#ifdef CONFIG_X86_64
+	const unsigned long long alignment = 16<<20;	/* 16M */
+	unsigned long long low_base = 0, low_size = 0;
+	unsigned long total_low_mem;
+	unsigned long long base;
+	int ret;
+
+	total_low_mem = memblock_mem_size(1UL<<(32-PAGE_SHIFT));
+	ret = parse_crashkernel_low(boot_command_line, total_low_mem,
+						&low_size, &base);
+	if (ret != 0 || low_size <= 0)
+		return;
+
+	low_base = memblock_find_in_range(low_size, (1ULL<<32),
+					low_size, alignment);
+
+	if (!low_base) {
+		pr_info("crashkernel low reservation failed - No suitable area found.\n");
+
+		return;
+	}
+
+	memblock_reserve(low_base, low_size);
+	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
+			(unsigned long)(low_size >> 20),
+			(unsigned long)(low_base >> 20),
+			(unsigned long)(total_low_mem >> 20));
+	crashk_low_res.start = low_base;
+	crashk_low_res.end   = low_base + low_size - 1;
+	insert_resource(&iomem_resource, &crashk_low_res);
+#endif
+}
+
 static void __init reserve_crashkernel(void)
 {
+	const unsigned long long alignment = 16<<20;	/* 16M */
 	unsigned long long total_mem;
 	unsigned long long crash_size, crash_base;
 	int ret;
@@ -523,8 +559,6 @@ static void __init reserve_crashkernel(void)
 
 	/* 0 means: find the address automatically */
 	if (crash_base <= 0) {
-		const unsigned long long alignment = 16<<20;	/* 16M */
-
 		/*
 		 *  kexec want bzImage is below CRASH_KERNEL_ADDR_MAX
 		 */
@@ -535,6 +569,7 @@ static void __init reserve_crashkernel(void)
 			pr_info("crashkernel reservation failed - No suitable area found.\n");
 			return;
 		}
+
 	} else {
 		unsigned long long start;
 
@@ -556,6 +591,9 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end   = crash_base + crash_size - 1;
 	insert_resource(&iomem_resource, &crashk_res);
+
+	if (crash_base >= (1ULL<<32))
+		reserve_crashkernel_low();
 }
 #else
 static void __init reserve_crashkernel(void)

trunk/include/linux/kexec.h

@@ -191,6 +191,7 @@ extern struct kimage *kexec_crash_image;
 /* Location of a reserved region to hold the crash kernel.
  */
 extern struct resource crashk_res;
+extern struct resource crashk_low_res;
 typedef u32 note_buf_t[KEXEC_NOTE_BYTES/4];
 extern note_buf_t __percpu *crash_notes;
 extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
@@ -199,6 +200,8 @@ extern size_t vmcoreinfo_max_size;
 
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
+int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
+		unsigned long long *crash_size, unsigned long long *crash_base);
 int crash_shrink_memory(unsigned long new_size);
 size_t crash_get_memory_size(void);
 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);

trunk/kernel/kexec.c

@@ -54,6 +54,12 @@ struct resource crashk_res = {
 	.end   = 0,
 	.flags = IORESOURCE_BUSY | IORESOURCE_MEM
 };
+struct resource crashk_low_res = {
+	.name  = "Crash kernel low",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_MEM
+};
 
 int kexec_should_crash(struct task_struct *p)
 {
@@ -1369,10 +1375,11 @@ static int __init parse_crashkernel_simple(char 		*cmdline,
  * That function is the entry point for command line parsing and should be
  * called from the arch-specific code.
  */
-int __init parse_crashkernel(char 		 *cmdline,
+static int __init __parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
 			     unsigned long long *crash_size,
-			     unsigned long long *crash_base)
+			     unsigned long long *crash_base,
+				const char *name)
 {
 	char 	*p = cmdline, *ck_cmdline = NULL;
 	char	*first_colon, *first_space;
@@ -1382,16 +1389,16 @@ int __init parse_crashkernel(char 		 *cmdline,
 	*crash_base = 0;
 
 	/* find crashkernel and use the last one if there are more */
-	p = strstr(p, "crashkernel=");
+	p = strstr(p, name);
 	while (p) {
 		ck_cmdline = p;
-		p = strstr(p+1, "crashkernel=");
+		p = strstr(p+1, name);
 	}
 
 	if (!ck_cmdline)
 		return -EINVAL;
 
-	ck_cmdline += 12; /* strlen("crashkernel=") */
+	ck_cmdline += strlen(name);
 
 	/*
 	 * if the commandline contains a ':', then that's the extended
@@ -1409,6 +1416,23 @@ int __init parse_crashkernel(char 		 *cmdline,
 	return 0;
 }
 
+int __init parse_crashkernel(char *cmdline,
+			     unsigned long long system_ram,
+			     unsigned long long *crash_size,
+			     unsigned long long *crash_base)
+{
+	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
+					"crashkernel=");
+}
+
+int __init parse_crashkernel_low(char *cmdline,
+			     unsigned long long system_ram,
+			     unsigned long long *crash_size,
+			     unsigned long long *crash_base)
+{
+	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
+					"crashkernel_low=");
+}
 
 static void update_vmcoreinfo_note(void)
 {