kernel memory interface
library provides a uniform interface
for accessing kernel virtual memory images, including live systems and crash
dumps. Access to live systems is via
while crash dumps can be examined
via the core file generated by
. 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.
() is first called to obtain a
descriptor for all subsequent calls.
- 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.,
()) has been incorporated into the
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
includes a routine,
, to return
(not print out) the error message corresponding to the most recent error
condition on the given descriptor.