NAME
kvm —
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
/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 gathered.
kvm_open() is first called to obtain a descriptor for all
subsequent calls.
FILES
- /dev/mem
- interface to physical memory
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 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 dependent.
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 ALSO
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)