feat: aarch64 port - fix build system obstacles, add exception handling, page tables

kernel/src/Pci/Pci.cpp

@@ -187,7 +187,20 @@ namespace Pci {
         Io::Out32(value, ConfigDataPort);
     }
 
+    // Drivers reach config space through the Legacy* calls below. Without
+    // an I/O address space (ARM) there is no CF8/CFC mechanism, so they use
+    // ECAM there, at the access's own width (16/8-bit writes must not
+    // read-modify-write a neighbouring RW1C register).
+    static bool EcamCovers(uint8_t bus);
+
+    static bool UseEcamForLegacy(uint8_t bus) {
+        return !Io::HasPortIo && EcamCovers(bus);
+    }
+
     uint32_t LegacyRead32(uint8_t bus, uint8_t device, uint8_t function, uint8_t offset) {
+        if (UseEcamForLegacy(bus)) {
+            return EcamRead32(g_ecamBase, bus, device, function, offset & 0xFC);
+        }
         g_legacyConfigLock.Acquire();
         uint32_t value = LegacyRead32Unlocked(bus, device, function, offset);
         g_legacyConfigLock.Release();
@@ -205,12 +218,20 @@ namespace Pci {
     }
 
     void LegacyWrite32(uint8_t bus, uint8_t device, uint8_t function, uint8_t offset, uint32_t value) {
+        if (UseEcamForLegacy(bus)) {
+            EcamWrite32(g_ecamBase, bus, device, function, offset & 0xFC, value);
+            return;
+        }
         g_legacyConfigLock.Acquire();
         LegacyWrite32Unlocked(bus, device, function, offset, value);
         g_legacyConfigLock.Release();
     }
 
     void LegacyWrite16(uint8_t bus, uint8_t device, uint8_t function, uint8_t offset, uint16_t value) {
+        if (UseEcamForLegacy(bus)) {
+            EcamWrite16(g_ecamBase, bus, device, function, offset & 0xFE, value);
+            return;
+        }
         g_legacyConfigLock.Acquire();
         uint32_t tmp = LegacyRead32Unlocked(bus, device, function, offset & 0xFC);
         int shift = (offset & 2) * 8;
@@ -221,6 +242,10 @@ namespace Pci {
     }
 
     void LegacyWrite8(uint8_t bus, uint8_t device, uint8_t function, uint8_t offset, uint8_t value) {
+        if (UseEcamForLegacy(bus)) {
+            EcamWrite8(g_ecamBase, bus, device, function, offset, value);
+            return;
+        }
         g_legacyConfigLock.Acquire();
         uint32_t tmp = LegacyRead32Unlocked(bus, device, function, offset & 0xFC);
         int shift = (offset & 3) * 8;