Reverse-engineering of the important bits of MasterAgent_ProcessPacket. By important, I mean gdb_query and *nothing else*.

MasterAgent_ProcessPacket.c

struct _globals {
	unsigned int isDebuggerPresent;
	unsigned short word_100D1378; //referenced in start()
	unsigned int dword_100523D8; //referenced in start()
	unsigned int tickStorage; //dword_100523D0, also referenced in start()
	char* stringStorage; //dword_1004F964
	
}
struct _globals globals;

typedef struct _MasterAgent_Packet {
	unsigned char command;
	
	//This is different depending on which command you pick
	//More REing will be needed
	
	//This is weird; it seems that this is a bunch of chars;
	//NOT a char* to somewhere else.
	//This is a dynamic length; the code can handle strings of other lengths.
	char s, u, p, p, o, r, t, e, d, nullchar;
	//TODO: re-check pointers, is there actually a nullchar?
	
	//the real memory location of param1 is dynamic, based on the length of the above string
	unsigned char param1;
	
} MasterAgent_Packet;

void MasterAgent_ProcessPacket(MasterAgent_Packet* packet) {
	if (packet->command == 0x71) {
		gdb_query(packet);
	}
}

void gdb_query(MasterAgent_Packet* packet) {
	int ret = __gdb_strncmp(packet->s, "Supported", 9);
	
	if (ret != 0) {
		//loc_203D9D4
		/*
			Involves "Attached", "1" and writestring	
		*/
	} else {
		if (packet->param1 == 0x3A) {
			//loc_203D9C8
			/*
				Many branches and __gdb_strncmps ensue.
				I can take a look if you *really* want...
			*/
		} else {
			//loc_203D80C
			globals.isDebuggerPresent = 1;
			globals.word_100D1378++;
			globals.tickStorage = globals.dword_100523D8 + OSGetSystemTick();
			
			//sub_2039158
			globals.stringStorage = 0;
			//return
			
			writestring("PacketSize=");
			
			char* buf = 0x100D855C;
			
			AFunctionThatIsProbablySnprintf(buf, 0x64, "%x", 0x800);
			
			writestring(buf);
			writestring(";qXfer:libraries:read+");
			writestring("COSver=");
			
			AFunctionThatIsProbablySnprintf(buf, 0x64, "%d", 0x5335);
			
			writestring(buf);
			
			SomeSortOfLoggingFunction(0);
		}
	}
}

//sub_203B6B4
//this doesn't look quite right
void writestring(char* string) {
	if (string[0] == 0) {
		globals.stringStorage = globals.stringStorage; //yes, really
		return;
	}
	int val = 0;
	int i = 0;
	while (globals.stringStorage < 0x7FC) {
		char* addr = 0x100D0000 | globals.stringStorage;
		globals.stringStorage++;
		*(addr + 0x6CF4) = string[i];
		i++;
		if (string[i] == 0) {
			break;
		}
	}
	//globals.stringStorage is written to memory down here
}