[PATCH] kdump : check flags field from drconf memory

[Chandru]

On a powerpc machine when memory is dynamically removed/added from an lpar, the 
corresponding flags field in the drconf memory reflects the same with the bits 
unset/set accordingly. The kernel does a check on these flags while booting. 
Following are the similar changes brought in to kexec-tools.  This makes 
kexec-tools to skip those memory regions that do not belong or are not 
assigned to the current partition ( but are available to dynamically add them 
back ). Without this patch (and with memory remove operation) copying vmcore 
fails with error as

Copying data                       : [ 84 %] readmem: Can't read the dump 
memory(/proc/vmcore). Bad address
read_pfn: Can't get the page data.


Signed-off-by : Chandru S <chandru at in.ibm.com>
---

diff -Naurp kexec-tools-orig//kexec/arch/ppc64/crashdump-ppc64.c 
kexec-tools/kexec/arch/ppc64/crashdump-ppc64.c
--- kexec-tools-orig//kexec/arch/ppc64/crashdump-ppc64.c	2008-10-14 
01:36:05.000000000 -0500
+++ kexec-tools/kexec/arch/ppc64/crashdump-ppc64.c	2008-10-17 
12:17:53.000000000 -0500
@@ -127,6 +127,7 @@ static int get_dyn_reconf_crash_memory_r
 	char fname[128], buf[32];
 	FILE *file;
 	int i, n;
+	uint32_t flags;
 
 	strcpy(fname, "/proc/device-tree/");
 	strcat(fname, "ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory");
@@ -150,10 +151,17 @@ static int get_dyn_reconf_crash_memory_r
 			return -1;
 		}
 
-		start = ((uint64_t *)buf)[0];
+		start = ((uint64_t *)buf)[DRCONF_ADDR];
 		end = start + lmb_size;
 		if (start == 0 && end >= (BACKUP_SRC_END + 1))
 			start = BACKUP_SRC_END + 1;
+
+		flags = (*((uint32_t *)&buf[DRCONF_FLAGS]));
+		/* skip this block if the reserved bit is set in flags (0x80)
+		   or if the block is not assigned to this partition (0x8) */
+		if ((flags & 0x80) || !(flags & 0x8))
+			continue;	
+
 		exclude_crash_region(start, end);
 	}
 	fclose(file);
diff -Naurp kexec-tools-orig//kexec/arch/ppc64/crashdump-ppc64.h 
kexec-tools/kexec/arch/ppc64/crashdump-ppc64.h
--- kexec-tools-orig//kexec/arch/ppc64/crashdump-ppc64.h	2008-10-14 
01:36:05.000000000 -0500
+++ kexec-tools/kexec/arch/ppc64/crashdump-ppc64.h	2008-10-17 
12:18:02.000000000 -0500
@@ -31,4 +31,7 @@ extern unsigned int rtas_size;
 uint64_t lmb_size;
 unsigned int num_of_lmbs;
 
+#define DRCONF_ADDR	0
+#define DRCONF_FLAGS	20
+
 #endif /* CRASHDUMP_PPC64_H */