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Manual Pages  — KLDSYM


kldsym – look up address by symbol name in a KLD



Standard C Library (libc, -lc)


#include <sys/param.h>
#include <sys/linker.h>

kldsym(int fileid, int command, void *data);


The kldsym() system call returns the address of the symbol specified in data in the module specified by fileid. If fileid is 0, all loaded modules are searched. Currently, the only command implemented is KLDSYM_LOOKUP.

The data argument is of the following structure:

struct kld_sym_lookup {
    int         version;        /* sizeof(struct kld_sym_lookup) */
    char        *symname;       /* Symbol name we are looking up */
    u_long      symvalue;
    size_t      symsize;

The version member is to be set by the code calling kldsym() to sizeof(struct kld_sym_lookup). The next two members, version and symname, are specified by the user. The last two, symvalue and symsize, are filled in by kldsym() and contain the address associated with symname and the size of the data it points to, respectively.


The kldsym function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.


The kldsym() system call will fail if:
  Invalid value in data->version or command.
  The fileid argument is invalid, or the specified symbol could not be found.


kldfind(2), kldfirstmod(2), kldload(2), kldnext(2), kldunload(2), modfind(2), modnext(2), modstat(2), kld(4)


The kldsym() system call first appeared in FreeBSD 3.0 .

KLDSYM (2) July 26, 2001

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A typical Unix /bin or /usr/bin directory contains a hundred different kinds of programs, written by dozens of egotistical programmers, each with its own syntax, operating paradigm, rules of use ... strategies for specifying options, and different sets of constraints.
— The Unix Haters' handbook