freebsd-dev/lib/libkvm/kvm_kerndisp.3
Leandro Lupori 38cf2a4334 Implement kvm_kerndisp
This change adds a new libkvm function, kvm_kerndisp(), that can be used to
retrieve the kernel displacement, that is the difference between the kernel's
base virtual address at run time and the kernel base virtual address specified
in the kernel image file.

This will be used by kgdb, to properly relocate kernel symbols, when needed.

Reviewed by:	jhb
Differential Revision:	https://reviews.freebsd.org/D23285
2020-02-06 13:21:59 +00:00

58 lines
2.1 KiB
Groff

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.Dd February 5, 2020
.Dt KVM_KERNDISP 3
.Os
.Sh NAME
.Nm kvm_kerndisp
.Nd get kernel displacement
.Sh LIBRARY
.Lb libkvm
.Sh SYNOPSIS
.In kvm.h
.Ft kssize_t
.Fn kvm_kerndisp "kvm_t *kd"
.Sh DESCRIPTION
.Fn kvm_kerndisp
returns the number of bytes by which the kernel referenced by
.Fa kd
is displaced.
This is the difference between the kernel's base virtual address at run time
and the kernel base virtual address specified in the kernel image file.
.Pp
Note that if the kernel is moved to a lower memory address,
the displacement will be negative.
.Sh RETURN VALUES
.Fn kvm_kerndisp
returns the number of bytes by which the kernel is displaced.
If the kernel is not displaced or if it is not possible to find the
displacement then 0 is returned.
.Sh SEE ALSO
.Xr kvm 3 ,
.Xr kvm_close 3 ,
.Xr kvm_open 3