crash utility help page:  whatis


NAME
  whatis - search symbol table for data or type information

SYNOPSIS
  whatis [struct | union | typedef | symbol] 

DESCRIPTION
  This command displays the definition of structures, unions, typedefs or
  text/data symbols.

    struct  a structure name. The output is the same as if the "struct"
            command was used.
     union  a union name. The output is the same as if the "union" command
            was used.
   typedef  a typedef name. If the typedef translates to a structure or union
            the output is the same as if the "struct" or "union" command
            was used. If the typedef is a primitive datatype, the one-line
            declaration is displayed.
    symbol  a kernel symbol.  

EXAMPLES
   Display the definition of a linux_binfmt structure:

    crash> whatis linux_binfmt
    struct linux_binfmt {
      struct linux_binfmt  *next;
      struct module  *module;
      int (*load_binary) ();
      int (*load_shlib) ();
      int (*core_dump) ();
    };
    
  Since a kmem_bufctl_t is typedef'd to be a kmem_bufctl_s structure, the
  output of the following two commands is identical:

    crash> whatis kmem_bufctl_s
    struct kmem_bufctl_s {
      union {
        struct kmem_bufctl_s  *buf_nextp;
        kmem_slab_t *buf_slabp;
        void *buf_objp;
      } u;
    };
    
    crash> whatis kmem_bufctl_t
    struct kmem_bufctl_s {
      union {
        struct kmem_bufctl_s *buf_nextp;
        kmem_slab_t *buf_slabp;
        void *buf_objp;
      } u;
    };
    SIZE: 4  (0x4)
    
  Display the type data of sys_read() and jiffies text and data symbols:

    crash> whatis sys_read
    ssize_t sys_read(unsigned int, char *, size_t);
 
    crash> whatis jiffies
    long unsigned int jiffies;

  Display definition of a kdev_t typedef:

    crash> whatis kdev_t
    typedef short unsigned int kdev_t;
    SIZE: 2  (0x2)