Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

KVM(3)                     Library Functions Manual                     KVM(3)

     kvm - kernel memory interface

     Kernel Data Access Library (libkvm, -lkvm)

     The kvm library provides a uniform interface for accessing kernel virtual
     memory images, including live systems and crash dumps.  Access to live
     systems is via /dev/mem while crash dumps can be examined via the core
     file generated by savecore(8).  The interface behaves identically in both
     cases.  Memory can be read and written, kernel symbol addresses can be
     looked up efficiently, and information about user processes can be

     kvm_open() is first called to obtain a descriptor for all subsequent

     /dev/mem  interface to physical memory

     The kvm interface was first introduced in SunOS.  A considerable number
     of programs have been developed that use this interface, making backward
     compatibility highly desirable.  In most respects, the Sun kvm interface
     is consistent and clean.  Accordingly, the generic portion of the
     interface (i.e., kvm_open(), kvm_close(), kvm_read(), kvm_write(), and
     kvm_nlist()) has been incorporated into the BSD interface.  Indeed, many
     kvm applications (i.e., debuggers and statistical monitors) use only this
     subset of the interface.

     The process interface was not kept.  This is not a portability issue
     since any code that manipulates processes is inherently machine

     Finally, the Sun kvm error reporting semantics are poorly defined.  The
     library can be configured either to print errors to stderr automatically,
     or to print no error messages at all.  In the latter case, the nature of
     the error cannot be determined.  To overcome this, the BSD interface
     includes a routine, kvm_geterr(3), to return (not print out) the error
     message corresponding to the most recent error condition on the given

     kvm_close(3), kvm_getargv(3), kvm_getenvv(3), kvm_geterr(3),
     kvm_getkernelname(3), kvm_getloadavg(3), kvm_getlwps(3), kvm_getprocs(3),
     kvm_nlist(3), kvm_open(3), kvm_openfiles(3), kvm_read(3), kvm_write(3)

NetBSD 9.99                   September 14, 2011                   NetBSD 9.99