[bootlin/training-materials updates] master: Boot time labs: use "-o" in grabserial to copy output to files (9f09dc9c)

[Michael Opdenacker]

Repository : https://github.com/bootlin/training-materials
On branch  : master
Link       : https://github.com/bootlin/training-materials/commit/9f09dc9c559dfdd0a15c26e327564deec753ecd1

>---------------------------------------------------------------

commit 9f09dc9c559dfdd0a15c26e327564deec753ecd1
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date:   Mon Oct 25 12:06:46 2021 +0200

    Boot time labs: use "-o" in grabserial to copy output to files
    
    Instead of copying and pasting from the terminal.
    
    Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>


>---------------------------------------------------------------

9f09dc9c559dfdd0a15c26e327564deec753ecd1
 labs/boot-time-application/boot-time-application.tex       |  4 ++--
 .../boot-time-filesystem-optimizations.tex                 |  4 ++--
 labs/boot-time-init-scripts/boot-time-init-scripts.tex     |  2 +-
 .../boot-time-software-measurement.tex                     | 14 +++++++++-----
 4 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/labs/boot-time-application/boot-time-application.tex b/labs/boot-time-application/boot-time-application.tex
index c6d77851..1e4f8aee 100644
--- a/labs/boot-time-application/boot-time-application.tex
+++ b/labs/boot-time-application/boot-time-application.tex
@@ -261,8 +261,8 @@ Notes:
       something on the screen to make the user wait.
 \end{itemize}
 
-Update and reboot your system through \code{grabserial}, and copy and
-paste your output to \code{boot-time-labs/logs/application.log}.
+Update and reboot your system through \code{grabserial}, copying the
+output to \code{~/logs/application.log}.
 Fill the below table with updated figures:
 
 \begin{tabular}{| l | l | r |}
diff --git a/labs/boot-time-filesystem-optimizations/boot-time-filesystem-optimizations.tex b/labs/boot-time-filesystem-optimizations/boot-time-filesystem-optimizations.tex
index cef63316..858bf9ea 100644
--- a/labs/boot-time-filesystem-optimizations/boot-time-filesystem-optimizations.tex
+++ b/labs/boot-time-filesystem-optimizations/boot-time-filesystem-optimizations.tex
@@ -30,8 +30,8 @@ Write the size of the \code{zImage} file in the first row of the below table:
 Go to \code{~/boot-time-labs/rootfs}. You should have a \code{rootfs}
 subdirectory where your root filesystem archive has been extracted.
 
-Boot your system with \code{grabserial}, store its output in
-\code{logs/filesystem-ext4.log}, and start filling the table below:
+Boot your system with \code{grabserial}, copying its output to
+\code{~/logs/filesystem-ext4.log}, and start filling the table below:
 
 \begin{tabular}{| l | l | l | r |}
   \hline
diff --git a/labs/boot-time-init-scripts/boot-time-init-scripts.tex b/labs/boot-time-init-scripts/boot-time-init-scripts.tex
index de515928..ed3fb7c7 100644
--- a/labs/boot-time-init-scripts/boot-time-init-scripts.tex
+++ b/labs/boot-time-init-scripts/boot-time-init-scripts.tex
@@ -395,7 +395,7 @@ You should observe substancial space reduction. Let's keep this option!
 Boot your system again.
 
 If everything works, it's time to boot the system again through
-\code{grabserial}, store the output to \code{logs/init-scripts.log}
+\code{grabserial}, copying the output to \code{~/logs/init-scripts.log}
 and update the below table:
 
 \begin{tabular}{| l | l | r |}
diff --git a/labs/boot-time-software-measurement/boot-time-software-measurement.tex b/labs/boot-time-software-measurement/boot-time-software-measurement.tex
index fa76f76d..5d82d62f 100644
--- a/labs/boot-time-software-measurement/boot-time-software-measurement.tex
+++ b/labs/boot-time-software-measurement/boot-time-software-measurement.tex
@@ -104,11 +104,19 @@ After reflashing the SD card, reset the board and check that you are
 getting the new message. You can now measure the time between starting
 \code{ffmpeg} and finishing processing the first frame.
 
+Before running \code{grabserial} again, let's create the {\code
+$HOME/logs/} in which we will store copies of the command's output:
+
+\begin{verbatim}
+mkdir ~/docs/
+\end{verbatim}
+
 Thanks to the last message, we can now stop \code{grabserial} when it's
 received, replacing the \code{-e} argument:
 
 \begin{verbatim}
-grabserial -d /dev/ttyUSB0 -m "U-Boot SPL" -t -e 30 -q "First frame decoded"
+grabserial -d /dev/ttyUSB0 -m "U-Boot SPL" -t -e 30 -q "First frame decoded" \
+           -o ~/logs/initial.log
 \end{verbatim}
 
 We now have a complete measurement of the initial boot time of the
@@ -118,10 +126,6 @@ useful to compare experiments, double check some measurements that
 are surprising and could have been copied in a wrong way, and
 investigate some differences between two different runs.
 
-So, create the {\code $HOME/boot-time-labs/logs} directory and copy and
-paste the \code{grabserial} output to the \code{initial.log} file in
-this directory.
-
 \section{Initial measurements}
 
 Now, take your calculator and fill the below table with the results from your experiments: