[bootlin/training-materials updates] master: Boot time labs: fix instructions to boot an uncompressed kernel (2d5973eb)

Michael Opdenacker michael.opdenacker at bootlin.com
Tue Apr 13 10:38:55 CEST 2021


Repository : https://github.com/bootlin/training-materials
On branch  : master
Link       : https://github.com/bootlin/training-materials/commit/2d5973ebb3e93bcc752a3ffe171b5063d0185cd4

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

commit 2d5973ebb3e93bcc752a3ffe171b5063d0185cd4
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date:   Tue Apr 13 10:38:55 2021 +0200

    Boot time labs: fix instructions to boot an uncompressed kernel
    
    Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>


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

2d5973ebb3e93bcc752a3ffe171b5063d0185cd4
 labs/boot-time-kernel/boot-time-kernel.tex | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/labs/boot-time-kernel/boot-time-kernel.tex b/labs/boot-time-kernel/boot-time-kernel.tex
index b7459dc2..b1447d96 100644
--- a/labs/boot-time-kernel/boot-time-kernel.tex
+++ b/labs/boot-time-kernel/boot-time-kernel.tex
@@ -179,10 +179,21 @@ the below table:
 \end{tabular}
 
 For the \code{None} row, there is no kernel configuration option, but
-all you have to do is take the \code{arch/arm/boot/Image} file, rename
-it to \code{zImage} on your SD card, and boot it. This option can make
-sense when the CPU is very slow and the storage is quite fast (like when
-you're booting Linux on a CPU emulated on an FPGA).
+all you have to do is take the \code{arch/arm/boot/Image} file, and make a
+\code{uImage} file out of it (as U-Boot's \code{bootz} command only
+works with \code{zImage} files):
+
+\begin{verbatim}
+sudo apt install u-boot-tools
+mkimage -A arm -O linux -C none  -T kernel -a 80008000 -e 80008000 \
+        -n 'Linux-5.11.11' -d arch/arm/boot/Image arch/arm/boot/uImage
+\end{verbatim}
+
+Then, in U-Boot, you will have to boot it with \code{bootm} instead of
+\code{bootz}.
+
+This option can make sense when the CPU is very slow and the storage is
+quite fast (like when you're booting Linux on a CPU emulated on an FPGA).
 
 At the end, keep the option that gives you the best boot time, and
 update the below table:




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