CODEWITHSUNDEEP
embedded-linuxyocto
Preeti
Preeti

Reputation: 753

Create patch and applying patch file in Yocto

I am trying to create a patch file for u-boot file and apply it to u-boot recipe in Yocto for my Avenger96 embedded board. I want to make some changes in the config file of u-boot and create a patch and add it to yocto recipe for u-boot. I am new to creating patches and would like to learn in detail.

The file which needs to be modified is in /build/tmp/work/dh_stm32mp1_dhcor_avenger96-poky-linux-gnueabi/u-boot-stm32mp1-dhsom/2021.01-r0/git/include/configs/stm32mp1.h. In this file I need to modify somethings like enabling CONFIG_BOOTCOUNT_LIMIT:

#define CONFIG_BOOTCOUNT_LIMIT
#define CONFIG_BOOTCOUNT_ENV

Is this the right way to enable u-boot variables?

And to add below lines to same file:

“bootlimit=5\0" \
"rootfspart=4\0" \
"bootargs=root=/dev/mmcblk0p${rootfspart} rdinit=/bin/kinit rw single\0" \
"altbootcmd=" \
"  echo Rollback to previous RootFs; "
"  if test ${rootfspart} = 4; " \
"    then setenv rootfspart 5; " \
"  else " \
"     setenv rootfspart 4; " \
"  fi; setenv bootcount 0; saveenv; " \
"  bootcmd\0" \

And then create a patch for this and apply this to u-boot recipe which is available in /sources/meta-board-bsp/recipes-bsp/u-boot. This recipe is cloned from git.

Now I have few questions:

  1. Should I directly edit stm32mp1.h file and add my changes or should I copy the original file to some temp location and then add new changes to copied file and then use git diff --no-index stm32mp1.h.orig stm32mp1.h > 0001-add-altbootcmd-u-boot.patch. Will this be sufficient to make it work?

  2. To add the patch file I need to copy this created patch file to /sources/meta-board-bsp/recipes-bsp/u-boot/files and include this in the SRC_URI:append:dh-stm32mp1-dhsom = " \ file://0001-add-altbootcmd-u-boot.patch \ " of the u-boot recipe /sources/meta-board-bsp/recipes-bsp/u-boot/u-boot_%.bbappend. Is this the right way?

  3. Before bitbaking my image recipe do I need to apply the patch by running anything particular to that patch or whether patching will happen automatically?

  4. Can I do the same thing from my custom layer instead of using meta-board-bsp? For example, my meta-custom layer structure is

    └── recipes-bsp
    └── u-boot
        ├── files
        │   ├── 0001-add-altbootcmd-u-boot.patch
        └── u-boot_%.bbappend

Will this also works?

Update

I followed the above steps and created a patch file and added it to /sources/meta-board-bsp/recipes-bsp/u-boot/u-boot_%.bbappend under SRC_URI:append:dh-stm32mp1-dhsom = " \ file://0001-add-altbootcmd-u-boot.patch \ ". Next I ran the image recipe and it completed without any error. But how can I check whether patch is successfully applied or not? My changes are not reflected in /build/tmp/work/dh_stm32mp1_dhcor_avenger96-poky-linux-gnueabi/u-boot-stm32mp1-dhsom/2021.01-r0/git/include/configs/stm32mp1.h. I expected it to be updated with new changes.

Can anyone please correct me if I am wrong here and how to make this work?

Your help will be much appreciated.

Thanks in advance.

P.S: I am using Ubuntu 20.04 with Yocto Project as build system. Please let me know if there are any missing info.

Upvotes: 0

Views: 3121

Answers (2)

KJ L
KJ L

Reputation: 175

I have tried it out yesterday, stm32mp1 using this repo https://github.com/STMicroelectronics/u-boot on their u-boot source code.

  1. I cloned the u-boot repo

  2. Create patch from this repo

    git format-patch -1 -o /home/user/<your meta-layer>/ <u-bootbbapend> directory

  3. bitake the U-boot recipe

  4. Validation: Navigate to u-boot WORKDIR

    bitbake -e u-boot | grep ^WORKDIR=
something like <Yocto directory>/stm32Yoctominimal/build-mp1/tmp/work/stm32mp1-poky-linux-gnueabi/u-boot-stm32mp/v2020.10-stm32mp-r2-r0

  5. go to the git in the u-boot WORKDIR,check the files git/include/configs/stm32mp1.h, if the patch file apply successfully, the file should have your changes.

  6. bitbake the image after you validate the changes take place.

Attached my POC here

In my POC, I have added a printf, when I boot my image in the board:

U-Boot 2020.10-stm32mp-r2-dirty (Oct 05 2020 - 15:15:32 +0000)

CPU: STM32MP157FAC Rev.Z
Model: STMicroelectronics STM32MP157F-DK2 Discovery Board
Board: stm32mp1 in trusted mode (st,stm32mp157f-dk2)
Stargazer OS U-boot Development Enablement

Upvotes: 1

Miguel Cano
Miguel Cano

Reputation: 89

I am surprised nobody mentioned devtool yet. I encourage you to check these online resources and learn how to use it. It makes the process of making changes to .bb recipes, adding patches, etc. much simpler.

Quick reference: https://wiki.koansoftware.com/index.php/Using_devtool_to_modify_recipes_in_Yocto Extended version: https://docs.yoctoproject.org/ref-manual/devtool-reference.html

The idea would be to leave the u-boot package as it comes from upstream and apply any changes you need (u-boot variables, .c/.cpp/.h modifications) through .patch files since they are custom options for your SW layer.

Upvotes: 1

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