[bootlin/training-materials updates] master: Revert "kernel-driver-development-debugging: Add dedicated slies about early printl WIP" (94cbe8d2)

Gregory CLEMENT gregory.clement at bootlin.com
Wed Sep 15 14:36:42 CEST 2021

Repository : https://github.com/bootlin/training-materials
On branch  : master
Link       : https://github.com/bootlin/training-materials/commit/94cbe8d27a7b17bbfbd8a270565fa1e9bc2e73c6


commit 94cbe8d27a7b17bbfbd8a270565fa1e9bc2e73c6
Author: Gregory CLEMENT <gregory.clement at bootlin.com>
Date:   Wed Sep 15 14:35:27 2021 +0200

    Revert "kernel-driver-development-debugging: Add dedicated slies about early printl WIP"
    This reverts commit 6515dccd9c160be9ee061cb4cbc8e080d1b98b98.
    The kernel debugging changes was WIP, so should not have been
    committed yet.


 .../kernel-driver-development-debugging.tex          | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/slides/kernel-driver-development-debugging/kernel-driver-development-debugging.tex b/slides/kernel-driver-development-debugging/kernel-driver-development-debugging.tex
index 0250fc1d..dc925b42 100644
--- a/slides/kernel-driver-development-debugging/kernel-driver-development-debugging.tex
+++ b/slides/kernel-driver-development-debugging/kernel-driver-development-debugging.tex
@@ -100,22 +100,6 @@ dev_info(&pdev->dev, "in probe\n");
-  \frametitle{Printing message early during the boot}
-  \begin{itemize}
-  \item Messages are visible only once the console driver has been initialized.
-  \item The console driver is simpler than a complete serial driver
-    and is initialize earlier than serial driver
-  \item But core subsystem are still initialized before, such as
-    memory, timer or interrupt, if a crash occurred there, then no
-    message are visible
-  \item on arm (32 bits) architecture most of the SoC implement the
-    \code{early_printk} support
-  \item \Activate it with kconfig{CONFIG_DEBUG_LL} and \kconfig{CONFIG_EARLYPRINTK} and add
-    \code{earlyprintk} to the kernel command line.
-  \end{itemize}
   A virtual filesystem to export debugging information to user space.
@@ -292,5 +276,9 @@ dev_info(&pdev->dev, "in probe\n");
     \item Is turned on by default
     \item To get oops messages with symbol names instead of raw addresses
+  \item On ARM, if your kernel doesn't boot or hangs without any
+    message, you can activate early debugging options
+    (\kconfig{CONFIG_DEBUG_LL} and \kconfig{CONFIG_EARLYPRINTK}), and add
+    \code{earlyprintk} to the kernel command line.

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