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authorZhouyi Zhou <zhouzhouyi@gmail.com>2017-07-07 16:51:45 +0800
committerJonathan Corbet <corbet@lwn.net>2017-07-17 14:49:01 -0600
commite604f1cb85367d2e5fd4cf253296d190996da81a (patch)
treec481484c5793fd6936f823054e3bb68e4795b51d /Documentation
parent14994a9bb4f4f042da9f1195ec76677552801eee (diff)
docs: disable KASLR when debugging kernel
commit 6807c84652b0 ("x86: Enable KASLR by default") enables KASLR by default on x86. While KASLR will confuse gdb which resolve kernel symbol address from symbol table of vmlinux. We should turn off KASLR for kernel debugging. Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Reviewed-by: Kieran Bingham <kbingham@kernel.org> Acked-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/dev-tools/gdb-kernel-debugging.rst6
1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/dev-tools/gdb-kernel-debugging.rst b/Documentation/dev-tools/gdb-kernel-debugging.rst
index 5e93c9bc6619..19df79286f00 100644
--- a/Documentation/dev-tools/gdb-kernel-debugging.rst
+++ b/Documentation/dev-tools/gdb-kernel-debugging.rst
@@ -31,11 +31,13 @@ Setup
CONFIG_DEBUG_INFO_REDUCED off. If your architecture supports
CONFIG_FRAME_POINTER, keep it enabled.
-- Install that kernel on the guest.
+- Install that kernel on the guest, turn off KASLR if necessary by adding
+ "nokaslr" to the kernel command line.
Alternatively, QEMU allows to boot the kernel directly using -kernel,
-append, -initrd command line switches. This is generally only useful if
you do not depend on modules. See QEMU documentation for more details on
- this mode.
+ this mode. In this case, you should build the kernel with
+ CONFIG_RANDOMIZE_BASE disabled if the architecture supports KASLR.
- Enable the gdb stub of QEMU/KVM, either