kvm_open(3KVM)						    Kernel VM Library Functions 					    kvm_open(3KVM)

NAME

       kvm_open, kvm_close - specify a kernel to examine

SYNOPSIS

       cc [ flag... ] file... -lkvm [ library...]
       #include <kvm.h>
       #include <fcntl.h>

       kvm_t *kvm_open(char *namelist, char *corefile, char *swapfile, int flag, char *errstr);

       int kvm_close(kvm_t *kd);

DESCRIPTION

       The  kvm_open()	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 argument in subsequent kernel VM function calls.

       The namelist argument specifies an unstripped executable file whose symbol table will be used to locate various	offsets  in  corefile.	If
       namelist  is NULL, 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
       file.

       The corefile 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 is NULL, the currently running kernel is accessed, using /dev/mem and /dev/kmem.

       The swapfile argument specifies a file that represents the swap device. If both corefile and swapfile are NULL, the swap device of the cur-
       rently running kernel is accessed.  Otherwise, if swapfile is NULL, kvm_open() may succeed but subsequent kvm_getu(3KVM) function calls may
       fail if the desired information is swapped out.

       The flag 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

       The errstr 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[0]. 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  ker-
       nel.

       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.

       The kvm_close() function closes all file descriptors that were associated with kd. These files are also closed on exit(2) and execve() (see
       exec(2)). kvm_close() also resets the proc pointer associated with kvm_nextproc(3KVM) and flushes any cached kernel data.

RETURN VALUES

       The kvm_open() function returns a non-null value suitable for use with subsequent kernel VM function calls. On failure, it returns NULL and
       no files are opened.

       The kvm_close() function returns 0 on success and -1 on failure.

FILES

       /dev/kmem

       /dev/ksyms

       /dev/mem

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Stable			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       savecore(1M),   exec(2),   exit(2),   pathconf(2),  getloadavg(3C),  kstat(3KSTAT),  kvm_getu(3KVM),  kvm_nextproc(3KVM),  kvm_nlist(3KVM),
       kvm_kread(3KVM), libkvm(3LIB),sysconf(3C), proc(4), attributes(5), lfcompile(5)

NOTES

       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 interfaces to access the running kernel must themselves be 64-bit applica-
       tions.

       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-dependent.

       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, see sysconf(3C), proc(4), kstat(3KSTAT), getloadavg(3C), and path-
       conf(2).

SunOS 5.10							    2 May 2002							    kvm_open(3KVM)