[Patch 6/7] powerpc: implement crashkernel=auto

[Amerigo Wang <amwang@redhat.com>]

Since in patch 2/7 we already implement the generic part, this will
add the rest part for powerpc.

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

---
Index: linux-2.6/arch/powerpc/include/asm/kexec.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/kexec.h
+++ linux-2.6/arch/powerpc/include/asm/kexec.h
@@ -39,6 +39,29 @@ typedef void (*crash_shutdown_t)(void);
 
 #ifdef CONFIG_KEXEC
 
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+#ifndef KEXEC_AUTO_RESERVED_SIZE
+#define KEXEC_AUTO_RESERVED_SIZE 1ULL<<28 /* 256M */
+#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 ppc, 0 means find the base address automatically. */
+	return 0;
+}
+#endif
+
 /*
  * This function is responsible for capturing register states if coming
  * via panic or invoking dump using sysrq-trigger.