Documentation/printk-formats.txt

   1 If variable is of Type,         use printk format specifier:
   2 ---------------------------------------------------------
   3                 int                     %d or %x
   4                 unsigned int            %u or %x
   5                 long                    %ld or %lx
   6                 unsigned long           %lu or %lx
   7                 long long               %lld or %llx
   8                 unsigned long long      %llu or %llx
   9                 size_t                  %zu or %zx
  10                 ssize_t                 %zd or %zx
  11
  12 Raw pointer value SHOULD be printed with %p.
  13
  14 u64 SHOULD be printed with %llu/%llx, (unsigned long long):
  15
  16         printk("%llu", (unsigned long long)u64_var);
  17
  18 s64 SHOULD be printed with %lld/%llx, (long long):
  19
  20         printk("%lld", (long long)s64_var);
  21
  22 If <type> is dependent on a config option for its size (e.g., sector_t,
  23 blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent
  24 for its size (e.g., tcflag_t), use a format specifier of its largest
  25 possible type and explicitly cast to it.  Example:
  26
  27         printk("test: sector number/total blocks: %llu/%llu\n",
  28                 (unsigned long long)sector, (unsigned long long)blockcount);
  29
  30 Reminder: sizeof() result is of type size_t.
  31
  32 Thank you for your cooperation and attention.
  33
  34
  35 By Randy Dunlap <rdunlap@xenotime.net>