linux/Documentation/printk-formats.txt
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   1If 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
  12Raw pointer value SHOULD be printed with %p.
  13
  14u64 SHOULD be printed with %llu/%llx, (unsigned long long):
  15
  16        printk("%llu", (unsigned long long)u64_var);
  17
  18s64 SHOULD be printed with %lld/%llx, (long long):
  19
  20        printk("%lld", (long long)s64_var);
  21
  22If <type> is dependent on a config option for its size (e.g., sector_t,
  23blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent
  24for its size (e.g., tcflag_t), use a format specifier of its largest
  25possible 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
  30Reminder: sizeof() result is of type size_t.
  31
  32Thank you for your cooperation and attention.
  33
  34
  35By Randy Dunlap <rdunlap@xenotime.net>
  36
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