[Patch 2/7] x86: implement crashkernel=auto

[Amerigo Wang <amwang@redhat.com>]

Implement "crashkernel=auto" for x86 first, other arch will be added in the
following patches.

Signed-off-by: WANG Cong <amwang@redhat.com>

---
Index: linux-2.6/kernel/kexec.c
===================================================================
--- linux-2.6.orig/kernel/kexec.c
+++ linux-2.6/kernel/kexec.c
@@ -37,6 +37,7 @@
 #include <asm/io.h>
 #include <asm/system.h>
 #include <asm/sections.h>
+#include <asm/setup.h>
 
 /* Per cpu memory for storing cpu states in case of system crash. */
 note_buf_t* crash_notes;
@@ -1297,6 +1298,38 @@ int __init parse_crashkernel(char 		 *cm
 
 	ck_cmdline += 12; /* strlen("crashkernel=") */
 
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+	if (strncmp(ck_cmdline, "auto", 4) == 0) {
+		unsigned long long size;
+		char tmp[32];
+
+		size = arch_default_crash_size(system_ram);
+		if (size != 0) {
+			*crash_size = size;
+			*crash_base = arch_default_crash_base();
+			size = scnprintf(tmp, sizeof(tmp), "%luM@%luM",
+					(unsigned long)(*crash_size)>>20,
+					(unsigned long)(*crash_base)>>20);
+			/* size can't be <= 4. */
+			if (likely((size - 4 + strlen(cmdline))
+					< COMMAND_LINE_SIZE - 1)) {
+				memmove(ck_cmdline + size, ck_cmdline + 4,
+					strlen(cmdline) - (ck_cmdline + 4 - cmdline) + 1);
+				memcpy(ck_cmdline, tmp, size);
+			}
+			return 0;
+		} else {
+			/*
+			 * We can't reserve memory auotmatcally,
+			 * remove "crashkernel=" from cmdline.
+			 */
+			ck_cmdline += 4; /* strlen("auto") */
+			memmove(ck_cmdline - 16, ck_cmdline,
+				strlen(cmdline) - (ck_cmdline - cmdline) + 1);
+			return -ENOMEM;
+		}
+	}
+#endif
 	/*
 	 * if the commandline contains a ':', then that's the extended
 	 * syntax -- if not, it must be the classic syntax
Index: linux-2.6/arch/x86/include/asm/kexec.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/kexec.h
+++ linux-2.6/arch/x86/include/asm/kexec.h
@@ -61,6 +61,29 @@
 # define KEXEC_ARCH KEXEC_ARCH_X86_64
 #endif
 
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+#ifndef KEXEC_AUTO_RESERVED_SIZE
+#define KEXEC_AUTO_RESERVED_SIZE 1ULL<<27 /* 128M */
+#endif
+#ifndef KEXEC_AUTO_THRESHOLD
+#define KEXEC_AUTO_THRESHOLD 1ULL<<32 /* 4G */
+#endif
+static inline
+unsigned long long arch_default_crash_size(unsigned long long total_size)
+{
+	if (total_size < KEXEC_AUTO_THRESHOLD)
+		return 0;
+	else
+		return KEXEC_AUTO_RESERVED_SIZE;
+}
+static inline
+unsigned long long arch_default_crash_base(void)
+{
+	/* On x86, 0 means find the base address automatically. */
+	return 0;
+}
+#endif
+
 /*
  * CPU does not save ss and sp on stack if execution is already
  * running in kernel mode at the time of NMI occurrence. This code