If variable is of Type, use printk format specifier:
---------------------------------------------------------
int %d or %x
unsigned int %u or %x
long %ld or %lx
unsigned long %lu or %lx
long long %lld or %llx
unsigned long long %llu or %llx
size_t %zu or %zx
ssize_t %zd or %zx
Raw pointer value SHOULD be printed with %p.
u64 SHOULD be printed with %llu/%llx, (unsigned long long):
printk("%llu", (unsigned long long)u64_var);
s64 SHOULD be printed with %lld/%llx, (long long):
printk("%lld", (long long)s64_var);
If <type> is dependent on a config option for its size (e.g., sector_t,
blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent
for its size (e.g., tcflag_t), use a format specifier of its largest
possible type and explicitly cast to it. Example:
printk("test: sector number/total blocks: %llu/%llu\n",
(unsigned long long)sector, (unsigned long long)blockcount);
Reminder: sizeof() result is of type size_t.
Thank you for your cooperation and attention.
By Randy Dunlap <rdunlap@xenotime.net>
Kernel Source / Documentation/printk-formats.txt