Start the main thread with COP0 Status.IE set

ps2xRuntime/include/ps2_runtime.h

@@ -150,10 +150,10 @@ struct alignas(16) R5900Context
 
         // Reset COP0 registers
         cop0_random = 47; // Start at maximum value
-        // cop0_status = 0x400000; // BEV set, ERL clear, kernel mode
-        // 0x00400000 = BEV (Boot Exception Vectors).
-        // 0x00000000 = Normal mode (after BIOS handoff).
-        cop0_status = 0x00000000;
+        // Status as the EE kernel leaves it at handoff. IE (bit 0) and EIE
+        // (bit 16) are separate enables and guest code reads both; libkernel's
+        // StartThread refuses to run while IE is clear.
+        cop0_status = 0x00010001; // EIE | IE
         cop0_prid = 0x00002e20; // CPU ID for R5900
 
         in_delay_slot = false;

ps2xRuntime/src/lib/ps2_runtime.cpp

@@ -491,7 +491,9 @@ PS2Runtime::PS2Runtime()
     }
 #endif
 
-    std::memset(&m_cpuContext, 0, sizeof(m_cpuContext));
+    // Assign rather than memset: R5900Context's constructor zeroes itself and
+    // then applies the COP0 reset values, which a memset here would discard.
+    m_cpuContext = R5900Context{};
 
     // R0 is always zero in MIPS
     m_cpuContext.r[0] = _mm_set1_epi32(0);