NAME

kvm_dump_mkheader, kvm_dump_wrtheader, kvm_dump_inval — crash dump support functions

LIBRARY

Kernel Data Access Library (libkvm, -lkvm)

SYNOPSIS

#include <kvm.h>

int
kvm_dump_mkheader(kvm_t *kd, off_t dump_off);

int
kvm_dump_wrtheader(kvm_t *kd, FILE *fp, int dumpsize);

int
kvm_dump_inval(kvm_t *kd);

DESCRIPTION

First note that the functions described here were designed to be used by savecore(8).

The function kvm_dump_mkheader() checks if the physical memory file associated with kd contains a valid crash dump header as generated by a dumping kernel. When a valid header is found, kvm_dump_mkheader() initializes the internal kvm data structures as if a crash dump generated by the savecore(8) program was opened. This has the intentional side effect of enabling the address translation machinery.

A call to kvm_dump_mkheader() will most likely be followed by a call to kvm_dump_wrtheader(). This function takes care of generating the generic header, the CORE_CPU section and the section header of the CORE_DATA section. The data is written to the file pointed at by fp. The dumpsize argument is only used to properly the set the segment size of the CORE_DATA section. Note that this function assumes that fp is positioned at file location 0. This function will not seek and therefore allows fp to be a file pointer obtained by zopen().

The kvm_dump_inval() function clears the magic number in the physical memory file associated with kd. The address translations must be enabled for this to work (thus assuming that kvm_dump_mkheader() was called earlier in the sequence).

RETURN VALUES

All functions except kvm_dump_mkheader() return 0 on success, -1 on failure. The function kvm_dump_mkheader() returns the size of the headers present before the actual dumpdata starts. If no valid headers were found but no fatal errors occurred, 0 is returned. On fatal errors the return value is -1.

In the case of failure, kvm_geterr(3) can be used to retrieve the cause of the error.

SEE ALSO

kvm(3), kvm_open(3)

HISTORY

These functions first appeared in NetBSD 1.2.