[PATCH] [ppc] Do not reserve cpu spin-table for crash kernel

[Suzuki K. Poulose]

As of now, the kexec reserves the spin-table for all the CPUs
on an SMP machine. The spin-table is pointed to by the 
cpu-release-addr property in the device-tree. Reserving the
spin-table in the crash kernel will cause a BUG(), if the table
lies outside the memory reserved for the crashkernel.

Disable reserving the spin-table regions and use maxcpus=1 to 
use only the crashing CPU to boot the crash kernel.

Signed-off-by: Suzuki K. Poulose <suzuki at in.ibm.com>
---

 kexec/arch/ppc/crashdump-powerpc.c |   19 +++++++++++++------
 kexec/arch/ppc/fixup_dtb.c         |    4 ++++
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/kexec/arch/ppc/crashdump-powerpc.c b/kexec/arch/ppc/crashdump-powerpc.c
index 1bef69b..4c8c75d 100644
--- a/kexec/arch/ppc/crashdump-powerpc.c
+++ b/kexec/arch/ppc/crashdump-powerpc.c
@@ -262,10 +262,19 @@ static void ulltoa(unsigned long long i, char *str)
 	}
 }
 
+/* Append str to cmdline */
+static void add_cmdline(char *cmdline, char *str)
+{
+	int cmdlen = strlen(cmdline) + strlen(str);
+	if (cmdlen > (COMMAND_LINE_SIZE - 1))
+		die("Command line overflow\n");
+	strcat(cmdline, str);
+}
+
 static int add_cmdline_param(char *cmdline, unsigned long long addr,
 				char *cmdstr, char *byte)
 {
-	int cmdlen, len, align = 1024;
+	int align = 1024;
 	char str[COMMAND_LINE_SIZE], *ptr;
 
 	/* Passing in =xxxK / =xxxM format. Saves space required in cmdline.*/
@@ -284,11 +293,8 @@ static int add_cmdline_param(char *cmdline, unsigned long long addr,
 	ptr += strlen(str);
 	ulltoa(addr, ptr);
 	strcat(str, byte);
-	len = strlen(str);
-	cmdlen = strlen(cmdline) + len;
-	if (cmdlen > (COMMAND_LINE_SIZE - 1))
-		die("Command line overflow\n");
-	strcat(cmdline, str);
+
+	add_cmdline(cmdline, str);
 
 	dbgprintf("Command line after adding elfcorehdr: %s\n", cmdline);
 
@@ -365,6 +371,7 @@ int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline,
 	 */
 	add_cmdline_param(mod_cmdline, elfcorehdr, " elfcorehdr=", "K");
 	add_cmdline_param(mod_cmdline, saved_max_mem, " savemaxmem=", "M");
+	add_cmdline(mod_cmdline, " maxcpus=1");
 	return 0;
 }
 
diff --git a/kexec/arch/ppc/fixup_dtb.c b/kexec/arch/ppc/fixup_dtb.c
index e9890a4..f832026 100644
--- a/kexec/arch/ppc/fixup_dtb.c
+++ b/kexec/arch/ppc/fixup_dtb.c
@@ -172,6 +172,9 @@ static void fixup_reserve_regions(struct kexec_info *info, char *blob_buf)
 		}
 	}
 
+#if 0
+	/* XXX: Do not reserve spin-table for CPUs. */
+
 	/* Add reserve regions for cpu-release-addr */
 	nodeoffset = fdt_node_offset_by_prop_value(blob_buf, -1, "device_type", "cpu", 4);
 	while (nodeoffset != -FDT_ERR_NOTFOUND) {
@@ -201,6 +204,7 @@ static void fixup_reserve_regions(struct kexec_info *info, char *blob_buf)
 		nodeoffset = fdt_node_offset_by_prop_value(blob_buf, nodeoffset,
 				"device_type", "cpu", 4);
 	}
+#endif
 
 out:
 	print_fdt_reserve_regions(blob_buf);