xv6/traps.h

// system defined:
#define T_DIVIDE     0		// divide error
#define T_DEBUG      1		// debug exception
#define T_NMI        2		// non-maskable interrupt
#define T_BRKPT      3		// breakpoint
#define T_OFLOW      4		// overflow
#define T_BOUND      5		// bounds check
#define T_ILLOP      6		// illegal opcode
#define T_DEVICE     7		// device not available 
#define T_DBLFLT     8		// double fault
/* #define T_COPROC  9 */	// reserved (not generated by recent processors)
#define T_TSS       10		// invalid task switch segment
#define T_SEGNP     11		// segment not present
#define T_STACK     12		// stack exception
#define T_GPFLT     13		// genernal protection fault
#define T_PGFLT     14		// page fault
/* #define T_RES    15 */	// reserved
#define T_FPERR     16		// floating point error
#define T_ALIGN     17		// aligment check
#define T_MCHK      18		// machine check
#define T_SIMDERR   19		// SIMD floating point error

// These are arbitrarily chosen, but with care not to overlap
// processor defined exceptions or interrupt vectors.
#define T_SYSCALL   48		// system call
#define T_DEFAULT   500		// catchall

#define IRQ_OFFSET      32	// IRQ 0 corresponds to int IRQ_OFFSET

#define IRQ_TIMER       18
#define IRQ_ERROR       19
#define IRQ_SPURIOUS    31