Core: Raise PI interrupt when accessing unmapped memory

Unmapped on the physical level, not the MMU level.

Fixes booting Game Boy Interface. Previously, Game Boy Interface thought
it was running on a Wii because accessing MEM2 didn't raise a PI
interrupt, and as a result tried to exit to the Homebrew Channel in a
way Dolphin's HLE doesn't recognize. (Dolphin's HLE catches jumps to
0x80001800, but GBI is running without address translation at this point
and therefore jumps to 0x00001800 instead.)

1 files changed, 17 insertions, 4 deletions

diff --git a/Source/Core/Core/PowerPC/MMU.cpp b/Source/Core/Core/PowerPC/MMU.cpp
index 934956a224..940e93c7ea 100644
--- a/Source/Core/Core/PowerPC/MMU.cpp
+++ b/Source/Core/Core/PowerPC/MMU.cpp
@@ -302,12 +302,21 @@ T MMU::ReadFromHardware(u32 em_address)
     return bswap(value);
   }
 
-  PanicAlertFmt("Unable to resolve read address {:x} PC {:x}", em_address, m_ppc_state.pc);
-  if (m_system.IsPauseOnPanicMode())
+  // Memory access error. Game Boy Interface relies on this to confirm that MEM2 isn't present.
+  // TODO: This interrupt is supposed to have associated cause and address registers.
+  m_system.GetProcessorInterface().SetInterrupt(ProcessorInterface::INT_CAUSE_PI);
+
+  // Don't show a panic alert for the specific access Game Boy Interface does.
+  if (em_address != 0x10000000 || (m_ppc_state.pc >> 28) != 0)
   {
-    m_system.GetCPU().Break();
-    m_ppc_state.Exceptions |= EXCEPTION_DSI | EXCEPTION_FAKE_MEMCHECK_HIT;
+    PanicAlertFmt("Unable to resolve read address {:x} PC {:x}", em_address, m_ppc_state.pc);
+    if (m_system.IsPauseOnPanicMode())
+    {
+      m_system.GetCPU().Break();
+      m_ppc_state.Exceptions |= EXCEPTION_DSI | EXCEPTION_FAKE_MEMCHECK_HIT;
+    }
   }
+
   return 0;
 }
 
@@ -492,6 +501,10 @@ void MMU::WriteToHardware(u32 em_address, const u32 data, const u32 size)
     return;
   }
 
+  // Memory access error.
+  // TODO: This interrupt is supposed to have associated cause and address registers.
+  m_system.GetProcessorInterface().SetInterrupt(ProcessorInterface::INT_CAUSE_PI);
+
   PanicAlertFmt("Unable to resolve write address {:x} PC {:x}", em_address, m_ppc_state.pc);
   if (m_system.IsPauseOnPanicMode())
   {