On 05/24/2012 11:39 AM, Suzuki K. Poulose wrote:
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<suz...@in.ibm.com>

Simon,

Any response on this one ?

I have tested this on a Currituck board (476, SMP) with a UP kernel.
Without this patch, the secondary kernel hits 'PANIC' in boot while
trying to reserve a memory(the spin table), outside the memory
range(crash reserve).


Thanks
Suzuki

---

  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);


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