From 14994a9bb4f4f042da9f1195ec76677552801eee Mon Sep 17 00:00:00 2001 From: Zhouyi Zhou Date: Fri, 7 Jul 2017 15:11:46 +0800 Subject: 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 Signed-off-by: Jonathan Corbet --- Documentation/dev-tools/kgdb.rst | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'Documentation/dev-tools') diff --git a/Documentation/dev-tools/kgdb.rst b/Documentation/dev-tools/kgdb.rst index 75273203a35a..d38be58f872a 100644 --- a/Documentation/dev-tools/kgdb.rst +++ b/Documentation/dev-tools/kgdb.rst @@ -348,6 +348,15 @@ default behavior is always set to 0. - ``echo 1 > /sys/module/debug_core/parameters/kgdbreboot`` - Enter the debugger on reboot notify. +Kernel parameter: ``nokaslr`` +----------------------------- + +If the architecture that you are using enable KASLR by default, +you should consider turning it off. KASLR randomizes the +virtual address where the kernel image is mapped and confuse +gdb which resolve kernel symbol address from symbol table +of vmlinux. + Using kdb ========= @@ -358,7 +367,7 @@ This is a quick example of how to use kdb. 1. Configure kgdboc at boot using kernel parameters:: - console=ttyS0,115200 kgdboc=ttyS0,115200 + console=ttyS0,115200 kgdboc=ttyS0,115200 nokaslr OR -- cgit v1.2.3-59-g8ed1b