docs: disable KASLR when debugging kernel

docs: disable KASLR when debugging kernel

[Natale Patriciello]

Hello,

Using KASLR will confuse gdb which resolves kernel symbol address from
symbol table of vmlinux. We should turn off KASLR for kernel
debugging, even in the older kernels in which its presence is
optional.

If you think it is correct, please apply to the kernels:

- 4.9   [ LTS ]
- 4.13 [ stable ]

The following commit already on the Linus tree:

- e604f1cb85367d2e5fd4cf253296d190996da81a ("docs: disable KASLR when
debugging kernel")

(stats):
 Documentation/dev-tools/gdb-kernel-debugging.rst | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Thank you
Natale

Re: docs: disable KASLR when debugging kernel

[Greg KH]

On Thu, Sep 21, 2017 at 04:20:22PM +0200, Natale Patriciello wrote:
> Hello,
> 
> Using KASLR will confuse gdb which resolves kernel symbol address from
> symbol table of vmlinux. We should turn off KASLR for kernel
> debugging, even in the older kernels in which its presence is
> optional.
> 
> If you think it is correct, please apply to the kernels:
> 
> - 4.9   [ LTS ]
> - 4.13 [ stable ]
> 
> The following commit already on the Linus tree:
> 
> - e604f1cb85367d2e5fd4cf253296d190996da81a ("docs: disable KASLR when
> debugging kernel")

As this option was only enabled by default in 4.12, let's keep this only
in 4.13 and newer, 4.9 doesn't matter here as to turn it on, you had to
know what you were doing :)

thanks,

greg k-h