fixed ODR violations to compile with gcc 11.4.1

src/devices/ioapic.c

@@ -53,6 +53,8 @@
    set to the default. */
 static volatile struct ioapic *ioapic;
 
+uint8_t ioapic_id;
+
 /* IO APIC MMIO structure: write reg, then read or write data. */
 struct ioapic
 {

src/devices/ioapic.h

@@ -3,7 +3,7 @@
 
 #include <stdint.h>
 
-uint8_t ioapic_id;
+extern uint8_t ioapic_id;
 
 void ioapic_init (void);
 void ioapic_enable (int irq, int cpu);

src/devices/lapic.c

@@ -88,6 +88,8 @@ static void microdelay (int);
 static void lapicw (int , int);
 static void sendipi (uint8_t , int);
 
+volatile uint32_t *lapic_base_addr;
+
 /* Initialize the local advanced interrupt controller. */
 void
 lapic_init (void)

src/devices/lapic.h

@@ -10,7 +10,7 @@
    lapic_base_addr stores the base address for the 
    local APIC. 
    This is initialized in mp.c, by parsing the MP Configuration Table */
-volatile uint32_t *lapic_base_addr;
+extern volatile uint32_t *lapic_base_addr;
 
 #define T_IPI 0xFB
 #define NUM_IPI 5

src/filesys/filesys.h

@@ -9,7 +9,7 @@
 #define ROOT_DIR_SECTOR 1       /* Root directory file inode sector. */
 
 /* Block device that contains the file system. */
-struct block *fs_device;
+extern struct block *fs_device;
 
 void filesys_init (bool format);
 void filesys_done (void);