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.Dd November 27, 2015 .Dt KVM_READ 3 .Os .Sh NAME .Nm kvm_read , .Nm kvm_read2 , .Nm kvm_write .Nd read or write kernel virtual memory .Sh LIBRARY .Lb libkvm .Sh SYNOPSIS n kvm.h .Ft ssize_t .Fn kvm_read "kvm_t *kd" "unsigned long addr" "void *buf" "size_t nbytes" .Ft ssize_t .Fn kvm_read2 "kvm_t *kd" "kvaddr_t addr" "void *buf" "size_t nbytes" .Ft ssize_t .Fn kvm_write "kvm_t *kd" "unsigned long addr" "const void *buf" "size_t nbytes" .Sh DESCRIPTION The .Fn kvm_read , .Fn kvm_read2 , and .Fn kvm_write functions are used to read and write kernel virtual memory (or a crash dump file). See .Fn kvm_open 3 for information regarding opening kernel virtual memory and crash dumps.
p The .Fn kvm_read and .Fn kvm_read2 functions transfer .Fa nbytes bytes of data from the kernel space address .Fa addr to .Fa buf . Conversely, .Fn kvm_write transfers data from .Fa buf to .Fa addr . Unlike their SunOS counterparts, these functions cannot be used to read or write process address spaces.
p The .Fn kvm_read2 function uses a different type
q Vt kvaddr_t for the .Fa addr argument to allow use of addresses larger than .Dv ULONG_MAX when examining non-native kernel images. .Sh RETURN VALUES Upon success, the number of bytes actually transferred is returned. Otherwise, -1 is returned. .Sh SEE ALSO .Xr kvm 3 , .Xr kvm_close 3 , .Xr kvm_getargv 3 , .Xr kvm_getenvv 3 , .Xr kvm_geterr 3 , .Xr kvm_getprocs 3 , .Xr kvm_nlist 3 , .Xr kvm_open 3 , .Xr kvm_openfiles 3 .Sh HISTORY The .Fn kvm_read2 function first appeared in .Fx 11.0 .