KVM(3) BSD Library Functions Manual KVM(3)NAMEkvm — kernel memory interface
LIBRARY
Kernel Data Access Library (libkvm, -lkvm)
DESCRIPTION
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 sysctl(3) for some functions, and mem(4) and kmem(4) for
other functions, while crash dumps can be examined via the core file gen‐
erated by savecore(8). The interface behaves similarly 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.
The kvm_open() function 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
includes a routine, kvm_geterr(3), to return (not print out) the error
message corresponding to the most recent error condition on the given
descriptor.
SEE ALSOkvm_close(3), kvm_getargv(3), kvm_getenvv(3), kvm_geterr(3),
kvm_getfiles(3), kvm_getloadavg(3), kvm_getprocs(3), kvm_getswapinfo(3),
kvm_nlist(3), kvm_open(3), kvm_openfiles(3), kvm_read(3), kvm_write(3),
sysctl(3), kmem(4), mem(4)BSD April 25, 2010 BSD
