ARM: guard masked symbol tables by default

Symbol tables masked with the loadAddrMask create redundant entries
that could conflict with kernel function events that rely on the
original addresses.  This patch guards the creation of those masked
symbol tables by default, with an option to enable them when needed
(for early-stage kernel debugging, etc.)

src/arch/arm/ArmSystem.py

@@ -65,3 +65,4 @@ class LinuxArmSystem(ArmSystem):
     machine_type = Param.ArmMachineType('RealView_PBX',
         "Machine id from http://www.arm.linux.org.uk/developer/machines/")
     atags_addr = Param.Addr(0x100, "Address where default atags structure should be written")
+    early_kernel_symbols = Param.Bool(False, "enable early kernel symbol tables before MMU")

src/arch/arm/linux/system.cc

@@ -114,10 +114,12 @@ LinuxArmSystem::initState()
     ArmSystem::initState();
 
     // Load symbols at physical address, we might not want
-    // to do this perminately, for but early bootup work
-    // it is helpfulp.
-    kernel->loadGlobalSymbols(kernelSymtab, loadAddrMask);
-    kernel->loadGlobalSymbols(debugSymbolTable, loadAddrMask);
+    // to do this permanently, for but early bootup work
+    // it is helpful.
+    if (params()->early_kernel_symbols) {
+        kernel->loadGlobalSymbols(kernelSymtab, loadAddrMask);
+        kernel->loadGlobalSymbols(debugSymbolTable, loadAddrMask);
+    }
 
     // Setup boot data structure
     AtagCore *ac = new AtagCore;