NAME
kvm_read, kvm_read2, kvm_write – read or write kernel virtual memory
LIBRARY
Kernel Data Access Library (libkvm, -lkvm)
SYNOPSIS
#include <kvm.h>
ssize_t
kvm_read(kvm_t *kd, unsigned long addr, void *buf, size_t nbytes);
ssize_t
kvm_read2(kvm_t *kd, kvaddr_t addr, void *buf, size_t nbytes);
ssize_t
kvm_write(kvm_t *kd, unsigned long addr, const void *buf, size_t nbytes);
DESCRIPTION
The kvm_read(), kvm_read2(), and kvm_write() functions are used to read and write kernel virtual memory (or a crash dump file). See kvm_open(3) for information regarding opening kernel virtual memory and crash dumps.
The kvm_read() and kvm_read2() functions transfer nbytes bytes of data from the kernel space address addr to buf. Conversely, kvm_write() transfers data from buf to addr. Unlike their SunOS counterparts, these functions cannot be used to read or write process address spaces.
The kvm_read2() function uses a different type (kvaddr_t) for the addr argument to allow use of addresses larger than ULONG_MAX when examining non-native kernel images.
RETURN VALUES
Upon success, the number of bytes actually transferred is returned. Otherwise, -1 is returned.
SEE ALSO
kvm(3), kvm_close(3), kvm_getargv(3), kvm_getenvv(3), kvm_geterr(3), kvm_getprocs(3), kvm_nlist(3), kvm_open(3), kvm_openfiles(3)
HISTORY
The kvm_read2() function first appeared in FreeBSD 11.0.