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KSYMS(4)                     Device Drivers Manual                    KSYMS(4)

NAME
     ksyms - kernel symbol table interface

SYNOPSIS
     pseudo-device ksyms

DESCRIPTION
     The /dev/ksyms character device provides a read-only interface to the
     current kernel symbol table.  It can be accessed either as a sequential
     file, where it looks like an executable file but with zero-sized text and
     data segments, or via ioctl(2).

     /dev/ksyms represents the symbol table at the time when the device is
     opened, and may not change until it is closed.

     The in-kernel symbol manager is designed to be able to handle any type of
     symbol table.  However, only elf(5) symbol tables are currently dealt
     with.

IOCTLS
     The ioctl(2) command codes below are defined in <sys/ksyms.h>.

     The (third) argument to the ioctl(2) should be a pointer to the type
     indicated.

           KIOCGSIZE (int)
                         Returns the total size of the current symbol table.
                         This should be used when allocating a buffer to read
                         in the whole symbol table to memory.

           KIOCGVALUE (struct ksyms_gvalue)
                         Returns the value for the given symbol name in a
                         symtab-independent fashion.

                               struct ksyms_gvalue {
                                       const char *kv_name;
                                       uint64_t kv_value;
                               };

                         The struct member kv_name should be set to the name
                         of the requested value, and upon return kv_value
                         contains the symbol value.

           KIOCGSYMBOL (struct ksyms_gsymbol)
                         Returns the complete symbol for the given symbol
                         name.

                               struct ksyms_gsymbol {
                                       const char *kg_name;
                                       void *kg_sym;
                               };

                         The struct member kg_name should be set to the name
                         of the requested symbol, and the found symbol will be
                         written to the kg_sym address.  It is the callers
                         responsibility to ensure that enough space for the
                         symbol is allocated.

FILES
     /dev/ksyms

SEE ALSO
     ioctl(2), nlist(3), elf(5)

HISTORY
     A ksyms device exists in many different operating systems.  This
     implementation is modelled in function after Solaris ksyms.  This ksyms
     driver was written by Anders Magnusson for NetBSD.

     The ksyms driver first appeared in NetBSD 2.0.

NetBSD 11.99                     July 27, 2024                    NetBSD 11.99