Ticket #7507: PreserveMBRdiskID.patch

src/add-ons/kernel/partitioning_systems/intel/PartitionMapWriter.cpp

@@ -8 +8 @@
 
 #include "PartitionMapWriter.h"
 
+#include <debug.h>
 #include <errno.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -134 +135 @@
         return B_BAD_VALUE;
 
     partition_table partitionTable;
+    status_t error;
+    error = _ReadBlock(0, partitionTable);
+    if (error != B_OK)
+        return error;
     if (writeBootCode) {
+        //the boot code must be small enough to fit in the code area
+        STATIC_ASSERT(sizeof(kBootCode)<=sizeof(partitionTable.code_area));
         partitionTable.clear_code_area();
         partitionTable.fill_code_area(kBootCode, sizeof(kBootCode));
-    } else {
-        status_t error = _ReadBlock(0, partitionTable);
-        if (error != B_OK)
-            return error;
     }
 
     partitionTable.signature = kPartitionTableSectorSignature;
@@ -152 +155 @@
         partition->GetPartitionDescriptor(descriptor);
     }
 
-    status_t error = _WriteBlock(0, partitionTable);
+    error = _WriteBlock(0, partitionTable);
     return error;
 }
 

src/add-ons/kernel/partitioning_systems/intel/PartitionMap.h

@@ -75 +75 @@
 
 // partition_table
 struct partition_table {
-    char                    code_area[446];
+    char                    code_area[440];
+    uint32                  disk_id;
+    uint16                  reserved;
     partition_descriptor    table[4];
     uint16                  signature;