KVM_OPEN(3KVM) Kernel VM Library Functions KVM_OPEN(3KVM)
kvm_open, kvm_close - specify a kernel to examine
... ] file
#include <fcntl.h> kvm_t *kvm_open
, char *corefile
, char *swapfile
, int flag
, char *errstr
); int kvm_close
function initializes a set of file descriptors to be used
in subsequent calls to kernel virtual memory ( VM) routines. It returns
a pointer to a kernel identifier that must be used as the kd
subsequent kernel VM function calls.
argument specifies an unstripped executable file whose
symbol table will be used to locate various offsets in corefile
. If namelist
, the symbol table of the currently running kernel is
used to determine offsets in the core image. In this case, it is up to
the implementation to select an appropriate way to resolve symbolic
references, for instance, using /dev/ksyms
as a default namelist
argument specifies a file that contains an image of physical
memory, for instance, a kernel crash dump file (see savecore(1M)
) or the
special device /dev/mem
. If corefile
, the currently running
kernel is accessed, using /dev/mem
argument specifies a file that represents the swap device.
If both corefile
, the swap device of the currently
running kernel is accessed. Otherwise, if swapfile
may succeed but subsequent kvm_getu(3KVM)
function calls may fail if the
desired information is swapped out.
function is used to specify read or write access for corefile
and may have one of the following values: O_RDONLY
open for reading O_RDWR
open for reading and writing
argument is used to control error reporting. If it is a null
pointer, no error messages will be printed. If it is non-null, it is
assumed to be the address of a string that will be used to prefix error
messages generated by kvm_open
. Errors are printed to stderr
. A useful
value to supply for errstr
would be argv
. This has the effect of
printing the process name in front of any error messages.
Applications using libkvm
are dependent on the underlying data model of
the kernel image, that is, whether it is a 32-bit or 64-bit kernel.
The data model of these applications must match the data model of the
kernel in order to correctly interpret the size and offsets of kernel
data structures. For example, a 32-bit application that uses the 32-bit
version of the libkvm
interfaces will fail to open a 64-bit kernel image.
Similarly, a 64-bit application that uses the 64-bit version of the libkvm
interfaces will fail to open a 32-bit kernel image.
function closes all file descriptors that were associated
. These files are also closed on exit(2)
() (see exec(2)
also resets the proc
pointer associated with kvm_nextproc(3KVM)
and flushes any cached kernel data.
function returns a non-null value suitable for use with
subsequent kernel VM function calls. On failure, it returns NULL
files are opened.
function returns 0 on success and -1 on failure.
FILES /dev/kmem /dev/ksyms /dev/mem
for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Interface Stability | Stable |
|MT-Level | Unsafe |
SEE ALSO savecore(1M)
Kernel core dumps should be examined on the platform on which they were
created. While a 32-bit application running on a 64-bit kernel can
examine a 32-bit core dump, a 64-bit application running on a 64-bit
kernel cannot examine a kernel core dump from the 32-bit system.
On 32-bit systems, applications that use libkvm
to access the running
kernel must be 32-bit applications. On systems that support both 32-bit
and 64-bit applications, applications that use the libkvm
access the running kernel must themselves be 64-bit applications.
Although the libkvm
API is Stable, the symbol names and data values that
can be accessed through this set of interfaces are Private and are
subject to ongoing change.
Applications using libkvm
are likely to be platform- and release-
Most of the traditional uses of libkvm
have been superseded by more
stable interfaces that allow the same information to be extracted more
efficiently, yet independent of the kernel data model. For examples,
, and pathconf(2)
May 2, 2002 KVM_OPEN(3KVM)