Multiple changes:

- Makefile: fix linker script path
- irq.c: `irqN()` stubs
- irq.h: fix missing header
- isr.h/isr.c extern `interrupt_handlers`
- utils.c: remove duplicate `memcmp`

Makefile

@@ -37,7 +37,7 @@ $(BUILD_DIR)/%.o: kernel/%.c
 	$(CC) -std=c11 -ffreestanding -nostdlib -fno-stack-protector -m32 -g -c -o $@ $<
 
 kernel: $(KERNEL_OBJ) | $(BUILD_DIR)
-	$(LD) -melf_i386 -Tbootloader/linker.ld -o $(BUILD_DIR)/kernel.elf $(KERNEL_OBJ)
+	$(LD) -melf_i386 -Tkernel/linker.ld -o $(BUILD_DIR)/kernel.elf $(KERNEL_OBJ)
 
 $(DISK_IMG): stage1 stage2 kernel
 	dd if=$(BUILD_DIR)/stage1.bin of=$@

kernel/irq.c

@@ -1,3 +1,4 @@
+#include "idt.h"
 #include "irq.h"
 #include "io.h"
 #include "isr.h"
@@ -7,6 +8,25 @@
 #define PIC2_CMD   0xA0
 #define PIC2_DATA  0xA1
 
+// FIXME: stubs
+void irq0() {}
+void irq1() {}
+void irq2() {}
+void irq3() {}
+void irq4() {}
+void irq5() {}
+void irq6() {}
+void irq7() {}
+void irq8() {}
+void irq9() {}
+void irq10() {}
+void irq11() {}
+void irq12() {}
+void irq13() {}
+void irq14() {}
+void irq15() {}
+// --- stubs end
+
 void irq_remap(void)
 {
     outb(PIC1_CMD, 0x11);   // ICW1 – edge triggered, cascade, need ICW4
@@ -31,8 +51,8 @@ void irq_install(void)
     irq_remap();
 
     /* Fill IRQ entries in the IDT (0x20 … 0x2F) */
-    extern void irq0(), irq1(), irq2(), irq3(), irq4(), irq5(), irq6(), irq7();
+    //extern void irq0(), irq1(), irq2(), irq3(), irq4(), irq5(), irq6(), irq7();
-    extern void irq8(), irq9(), irq10(), irq11(), irq12(), irq13(), irq14(), irq15();
+    //extern void irq8(), irq9(), irq10(), irq11(), irq12(), irq13(), irq14(), irq15();
 
     idt_set_gate(0x20, (uint32_t)irq0);
     idt_set_gate(0x21, (uint32_t)irq1);

kernel/irq.h

@@ -1,6 +1,8 @@
 #ifndef IRQ_H
 #define IRQ_H
 
+#include "types.h"
+
 void irq_remap(void);
 void irq_install(void);
 void irq_handler(uint32_t int_num);

kernel/isr.c

@@ -4,7 +4,7 @@
 #include "io.h"
 #include "print.h"
 
-static isr_callback_t interrupt_handlers[MAX_INTERRUPTS] = { 0 };
+isr_callback_t interrupt_handlers[MAX_INTERRUPTS] = { 0 };
 
 void isr_handler(uint32_t int_num, uint32_t err_code) {
     terminal_write("Interrupt occurred: ");

kernel/isr.h

@@ -6,6 +6,7 @@
 #define MAX_INTERRUPTS 256
 
 typedef void (*isr_callback_t)(void);
+extern isr_callback_t interrupt_handlers[MAX_INTERRUPTS];
 
 void isr_handler(uint32_t int_num, uint32_t err_code);
 void register_interrupt_handler(uint8_t n, isr_callback_t handler);

kernel/memory.h

@@ -11,7 +11,7 @@ extern "C" {
 /* C11 / POSIX-2004 signatures */
 void *memcpy(void *restrict dst, const void *restrict src, size_t n);
 void *memmove(void *dst, const void *src, size_t n);
-/*int   memcmp(const void *s1, const void *s2, size_t n); */
+int   memcmp(const void *s1, const void *s2, size_t n);
 
 /* Optional fast-path using 32-bit loads (x86 only) */
 #if defined(__i386__) && !defined(MEMORY_NO_OPT)

kernel/utils.c

@@ -77,16 +77,6 @@ char* utoa(unsigned int value, char* str, int base) {
     return str;
 }
 
-int memcmp(const void *ptr1, const void *ptr2, size_t num) {
-    const uint8_t *p1 = ptr1, *p2 = ptr2;
-    for (size_t i = 0; i < num; i++) {
-        if (p1[i] != p2[i]) {
-            return p1[i] < p2[i] ? -1 : 1;
-        }
-    }
-    return 0;
-}
-
 void *memset(void *dest, int value, size_t len) {
     unsigned char *ptr = (unsigned char *)dest;
     while (len-- > 0)

kernel/utils.h

@@ -9,7 +9,6 @@ char* itoa(int value, char* str, int base);
 // Convert unsigned integer to string (base is typically 10, 16, etc.)
 char* utoa(unsigned int value, char* str, int base);
 
-int memcmp(const void *ptr1, const void *ptr2, size_t num);
 void *memset(void *dest, int value, size_t len);
 
 #endif // UTILS_H