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
sysctl(3) for some functions, and
mem(4) and
kmem(4) for other functions,
while crash dumps can be examined via the core file generated 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 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_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)