[FE training-materials-updates] Kernel compile lab: add tips for checking the kernel version and compile date

[Michael Opdenacker]

Repository : git://git.free-electrons.com/training-materials.git
On branch  : master
Link       : http://git.free-electrons.com/training-materials/commit/?id=f8506c9b34b743197a9a5f7f631106a5a7b6e115

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commit f8506c9b34b743197a9a5f7f631106a5a7b6e115
Author: Michael Opdenacker <michael.opdenacker at free-electrons.com>
Date:   Wed Dec 7 22:07:44 2016 +0100

    Kernel compile lab: add tips for checking the kernel version and compile date
    
    Signed-off-by: Michael Opdenacker <michael.opdenacker at free-electrons.com>


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f8506c9b34b743197a9a5f7f631106a5a7b6e115
 .../kernel-compiling-and-nfs-booting.tex           | 23 ++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/labs/kernel-compiling-and-nfs-booting/kernel-compiling-and-nfs-booting.tex b/labs/kernel-compiling-and-nfs-booting/kernel-compiling-and-nfs-booting.tex
index cfd7fc1..06787ec 100644
--- a/labs/kernel-compiling-and-nfs-booting/kernel-compiling-and-nfs-booting.tex
+++ b/labs/kernel-compiling-and-nfs-booting/kernel-compiling-and-nfs-booting.tex
@@ -168,6 +168,29 @@ If the kernel fails to mount the NFS filesystem, look carefully at the
 error messages in the console. If this doesn't give any clue, you can
 also have a look at the NFS server logs in \code{/var/log/syslog}.
 
+\section{Checking the kernel version}
+
+It's often a good idea to make sure you booted the right kernel.
+By mistake, you could have booted a kernel previously stored in flash
+(typically through a default boot command in U-Boot), or forgotten to 
+update the kernel image in \code{/var/lib/tftpboot}.
+
+This could explain some unexpected behaviour.
+
+There are two ways of checking your kernel version:
+\begin{itemize}
+\item By looking at the first kernel messages
+\item By running the \code{uname -a} command after booting Linux. 
+\end{itemize}
+
+In both cases, you will not only know the kernel version, but also
+the date when the kernel was compiled and the name of the user who
+did it.
+
+Similarly, you can also check the command line actually received by
+the kernel, either by looking at the first boot messages, or once you
+have reached a command line shell, by running \code{cat /proc/cmdline}.
+
 \section{Automate the boot process}
 
 To avoid typing the same U-boot commands over and over again each time