KVM(3) BSD Programmer's Manual KVM(3)NAMEkvm - kernel memory interface
DESCRIPTION
The kvm(3) library provides a uniform interface for accessing kernel vir-
tual memory images, including live systems and crashdumps. Access to
live systems is via /dev/mem while crashdumps 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
gathered.
kvm_open() is first called to obtain a descriptor for all subsequent
calls.
COMPATIBILITY
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 inter-
face (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 depen-
dent.
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 in-
cludes a routine, kvm_geterr(3), to return (not print out) the error
message corresponding to the most recent error condition on the given de-
scriptor.
SEE ALSOkvm_close(3), kvm_getargv(3), kvm_getenvv(3), kvm_geterr(3),
kvm_getloadavg(3), kvm_getprocs(3), kvm_nlist(3), kvm_open(3),
kvm_openfiles(3), kvm_read(3), kvm_write(3)BSDI BSD/OS June 4, 1993 1
