Yocto migration meta-barebox -> walnascar

Yocto migration meta-barebox -> walnascar

[Konstantin Kletschke]

Dear barebox people,
Happy New Year everybody :-)

I used up until scarthgap https://github.com/menschel-d/meta-barebox

In our meta layer we have config in distro conf like this:

ABREBOX_CONFIG:beaglebone-yocto = "omap_defconfig"
BAREBOX_CONFIG:pn-barebox-pbl:beaglebone-yocto = "am335x_mlo_defconfig"
BAREBOX_IMAGE_SRC:beaglebone-yocto = "images/barebox-am33xx-beaglebone.img"
BAREBOX_IMAGE_SRC:pn-barebox-pbl:beaglebone-yocto = "images/barebox-am33xx-beaglebone-mlo.img"
RDEPENDS:barebox:beaglebone-yocto += "barebox-pbl"
COMPATIBLE_MACHINE:pn-barebox:beaglebone-yocto = "beaglebone-yocto"
COMPATIBLE_MACHINE:pn-barebox-pbl:beaglebone-yocto = "beaglebone-yocto"
PREFERRED_PROVIDER_virtual/bootloader = "barebox"

And a append recipe mainly with patches creating our custom
configuration.

Now I learned, barebox went into openembedded-core, this is great news!

I ditched the meta-barebox, tried my best, needed to remove alle configs
regarding "-pbl" and compiled:
ERROR: Nothing RPROVIDES 'barebox-pbl'
 (but /home/konsti/Melitta/scarthgap/meta/recipes-bsp/barebox/barebox.bb
 RDEPENDS on or otherwise requires it)



Now I get several ~580kB img files in the deployment images directory,
"ours" seems to be barebox-am33xx-beaglebone.img. File size is plausible
for the ex barebox.bin and strings suggest our insidem2m stuff to
boot/tftp/nfs landed up in it.

Where is the MLO part? Is barebox-am33xx-beaglebone.img the 1:1
barebox.bin equivalent?

We are used to create a partition table, first partition is vfat type
0x0c, MLO and barebox.bin are put there, works.

Kind Regards
Konstantin Kletschke


-- 
INSIDE M2M GmbH
Konstantin Kletschke
Berenbosteler Straße 76 B
30823 Garbsen

Telefon: +49 (0) 5137 90950136
Mobil: +49 (0) 151 15256238
Fax: +49 (0) 5137 9095010

konstantin.kletschke@inside-m2m.de
http://www.inside-m2m.de 

Geschäftsführung: Michael Emmert, Derek Uhlig
HRB: 111204, AG Hannover

Re: Yocto migration meta-barebox -> walnascar

[Marco Felsch]

Hi Konstantin,

On 26-01-06, Konstantin Kletschke wrote:
> Dear barebox people,
> Happy New Year everybody :-)

Thanks, happy new year to you too :)

> I used up until scarthgap https://github.com/menschel-d/meta-barebox
> 
> In our meta layer we have config in distro conf like this:
> 
> ABREBOX_CONFIG:beaglebone-yocto = "omap_defconfig"
> BAREBOX_CONFIG:pn-barebox-pbl:beaglebone-yocto = "am335x_mlo_defconfig"
> BAREBOX_IMAGE_SRC:beaglebone-yocto = "images/barebox-am33xx-beaglebone.img"
> BAREBOX_IMAGE_SRC:pn-barebox-pbl:beaglebone-yocto = "images/barebox-am33xx-beaglebone-mlo.img"
> RDEPENDS:barebox:beaglebone-yocto += "barebox-pbl"
> COMPATIBLE_MACHINE:pn-barebox:beaglebone-yocto = "beaglebone-yocto"
> COMPATIBLE_MACHINE:pn-barebox-pbl:beaglebone-yocto = "beaglebone-yocto"
> PREFERRED_PROVIDER_virtual/bootloader = "barebox"
> 
> And a append recipe mainly with patches creating our custom
> configuration.
> 
> Now I learned, barebox went into openembedded-core, this is great news!
> 
> I ditched the meta-barebox, tried my best, needed to remove alle configs
> regarding "-pbl" and compiled:
> ERROR: Nothing RPROVIDES 'barebox-pbl'
>  (but /home/konsti/Melitta/scarthgap/meta/recipes-bsp/barebox/barebox.bb
>  RDEPENDS on or otherwise requires it)

Which barebox version do you use?

> Now I get several ~580kB img files in the deployment images directory,
> "ours" seems to be barebox-am33xx-beaglebone.img. File size is plausible
> for the ex barebox.bin and strings suggest our insidem2m stuff to
> boot/tftp/nfs landed up in it.
> 
> Where is the MLO part? Is barebox-am33xx-beaglebone.img the 1:1
> barebox.bin equivalent?

Ahmad added the support for a single barebox binary:
 - https://lore.barebox.org/barebox/20250422052635.3423961-1-a.fatoum@pengutronix.de/

IIRC the purpose of the patchset was exactly to fulfill an easier Yocto
integration since the beaglebone is one of the oe-core real test hw.

> We are used to create a partition table, first partition is vfat type
> 0x0c, MLO and barebox.bin are put there, works.

Since the single image approach targets only the SD/MMC boot, the
standalone MLO image should be still possible.

Regards,
  Marco

> 
> Kind Regards
> Konstantin Kletschke
> 
> 
> -- 
> INSIDE M2M GmbH
> Konstantin Kletschke
> Berenbosteler Straße 76 B
> 30823 Garbsen
> 
> Telefon: +49 (0) 5137 90950136
> Mobil: +49 (0) 151 15256238
> Fax: +49 (0) 5137 9095010
> 
> konstantin.kletschke@inside-m2m.de
> http://www.inside-m2m.de 
> 
> Geschäftsführung: Michael Emmert, Derek Uhlig
> HRB: 111204, AG Hannover
> 
> 
> 

-- 
#gernperDu 
#CallMeByMyFirstName

Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | https://www.pengutronix.de/ |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-9    |

Re: Yocto migration meta-barebox -> walnascar

[Konstantin Kletschke]

On Tue, Jan 06, 2026 at 10:52:53AM +0100, Marco Felsch wrote:

> Which barebox version do you use?

It should be 2025.02.0.
I switched to walnascar and this should be the part used:
https://git.yoctoproject.org/poky/tree/meta/recipes-bsp/barebox?h=walnascar

> Ahmad added the support for a single barebox binary:
>  - https://lore.barebox.org/barebox/20250422052635.3423961-1-a.fatoum@pengutronix.de/
> 
> IIRC the purpose of the patchset was exactly to fulfill an easier Yocto
> integration since the beaglebone is one of the oe-core real test hw.

That's is very interesting.
What I did not get, yet:
So we can keep our partition scheme, the CPUs bootloader is searching
hardcoded for partition table -> first vfat -> MLO.
Then barebox-am33xx-beaglebone.img is put there as MLO?

> Since the single image approach targets only the SD/MMC boot, the
> standalone MLO image should be still possible.

 Can this be switched on/off somewere in the yocto framework so the old
 MLO/barebox.bin pair is genereated?

Regards
Konstantin

Re: Yocto migration meta-barebox -> walnascar

[Ahmad Fatoum]

Hello Konstantin,

On 1/6/26 11:12 AM, Konstantin Kletschke wrote:
> On Tue, Jan 06, 2026 at 10:52:53AM +0100, Marco Felsch wrote:
> 
>> Which barebox version do you use?
> 
> It should be 2025.02.0.
> I switched to walnascar and this should be the part used:
> https://git.yoctoproject.org/poky/tree/meta/recipes-bsp/barebox?h=walnascar
> 
>> Ahmad added the support for a single barebox binary:
>>  - https://lore.barebox.org/barebox/20250422052635.3423961-1-a.fatoum@pengutronix.de/
>>
>> IIRC the purpose of the patchset was exactly to fulfill an easier Yocto
>> integration since the beaglebone is one of the oe-core real test hw.
> 
> That's is very interesting.
> What I did not get, yet:
> So we can keep our partition scheme, the CPUs bootloader is searching
> hardcoded for partition table -> first vfat -> MLO.
> Then barebox-am33xx-beaglebone.img is put there as MLO?

When enabled, the same barebox build generates two images:
barebox-am33xx-beaglebone-mlo.mmc.img -> MLO
barebox-am33xx-beaglebone.img -> barebox.bin

Both are placed in the VFAT.

>> Since the single image approach targets only the SD/MMC boot, the
>> standalone MLO image should be still possible.

I didn't test it on eMMC and I suspect it needs light tweaking to work
there. If you are happy to test, I can find some time later to send a patch.

>  Can this be switched on/off somewere in the yocto framework so the old
>  MLO/barebox.bin pair is genereated?

For your old setup, you will need two recipes. Just define your own
barebox.bb and barebox-pbl.bb recipes and inherit barebox in each and
use different configs. All the core logic is in a barebox.bbclass to
allow you to easily create your own recipes.

This allows you also to use a newer version than v2025.02.0 for example
v2025.09.1, which is going to be maintained for longer than just a month.

Cheers,
Ahmad

> 
> Regards
> Konstantin
> 
> 

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |

Re: Yocto migration meta-barebox -> walnascar

[Konstantin Kletschke]

Hello Ahmad!

On Tue, Jan 06, 2026 at 12:33:21PM +0100, Ahmad Fatoum wrote:

> When enabled, the same barebox build generates two images:
> barebox-am33xx-beaglebone-mlo.mmc.img -> MLO
> barebox-am33xx-beaglebone.img -> barebox.bin
> 
> Both are placed in the VFAT.

I do not necessaryly need two images, if booting is now done with a
combined one, which is new, if I understood this correct.

In my images deploy dir the following images showed up after my
migration to walnascar away from the meta-barebox layer which is not
used anymore.

barebox-am33xx-afi-gf.img
barebox-am33xx-baltos.img
barebox-am33xx-beaglebone.img
barebox-am33xx-myirtech.img
barebox-am33xx-phytec-phycard.img
barebox-am33xx-phytec-phycore-emmc.img
barebox-am33xx-phytec-phycore-no-eeprom.img
barebox-am33xx-phytec-phycore-no-spi-no-eeprom.img
barebox-am33xx-phytec-phycore-no-spi.img
barebox-am33xx-phytec-phycore.img
barebox-am33xx-phytec-phyflex-no-eeprom.img
barebox-am33xx-phytec-phyflex-no-spi-no-eeprom.img
barebox-am33xx-phytec-phyflex-no-spi.img
barebox-am33xx-phytec-phyflex.img
barebox-am35xx-pfc-750-820x.img
barebox-beagleboard.img
barebox-dt-2nd.img

And that is, when I wondered myself, if - in our case - barebox-am33xx-beaglebone.img
is going to be named MLO and put into the vfat boot partition or if I
have something missing or done wrong, which is absolutely possible, of
course!

So, no *mlo* file.

> For your old setup, you will need two recipes. Just define your own
> barebox.bb and barebox-pbl.bb recipes and inherit barebox in each and
> use different configs. All the core logic is in a barebox.bbclass to
> allow you to easily create your own recipes.

So only using this approach with two barebox.bb and barebox-pbl.bb I
would get an additional *mlo* file, right?
As said, if I can omit this approach this is fine by me.

Regards
Konsti



-- 
INSIDE M2M GmbH
Konstantin Kletschke
Berenbosteler Straße 76 B
30823 Garbsen

Telefon: +49 (0) 5137 90950136
Mobil: +49 (0) 151 15256238
Fax: +49 (0) 5137 9095010

konstantin.kletschke@inside-m2m.de
http://www.inside-m2m.de 

Geschäftsführung: Michael Emmert, Derek Uhlig
HRB: 111204, AG Hannover

Re: Yocto migration meta-barebox -> walnascar

[Ahmad Fatoum]

Hi,

On 1/6/26 2:10 PM, Konstantin Kletschke wrote:
> Hello Ahmad!
> 
> On Tue, Jan 06, 2026 at 12:33:21PM +0100, Ahmad Fatoum wrote:
> 
>> When enabled, the same barebox build generates two images:
>> barebox-am33xx-beaglebone-mlo.mmc.img -> MLO
>> barebox-am33xx-beaglebone.img -> barebox.bin
>>
>> Both are placed in the VFAT.
> 
> I do not necessaryly need two images, if booting is now done with a
> combined one, which is new, if I understood this correct.

There must be a separate MLO image that is small enough to fit into
SRAM. So you still need two images, the only difference is if you build
barebox twice with two different configs or build it only once.

Both are possible, you just need to adapt your recipe(s) accordingly.
For you old way of doing things, you need two recipes, each with its own
config.
> In my images deploy dir the following images showed up after my
> migration to walnascar away from the meta-barebox layer which is not
> used anymore.
> 
> barebox-am33xx-afi-gf.img
> barebox-am33xx-baltos.img
> barebox-am33xx-beaglebone.img
> barebox-am33xx-myirtech.img
> barebox-am33xx-phytec-phycard.img
> barebox-am33xx-phytec-phycore-emmc.img
> barebox-am33xx-phytec-phycore-no-eeprom.img
> barebox-am33xx-phytec-phycore-no-spi-no-eeprom.img
> barebox-am33xx-phytec-phycore-no-spi.img
> barebox-am33xx-phytec-phycore.img
> barebox-am33xx-phytec-phyflex-no-eeprom.img
> barebox-am33xx-phytec-phyflex-no-spi-no-eeprom.img
> barebox-am33xx-phytec-phyflex-no-spi.img
> barebox-am33xx-phytec-phyflex.img
> barebox-am35xx-pfc-750-820x.img
> barebox-beagleboard.img
> barebox-dt-2nd.img

These are all second stage barebox images (barebox.bin).
To use the MLO as you did before, you need a second recipe where you
build am335x_mlo_defconfig or w/e your config is.


> And that is, when I wondered myself, if - in our case - barebox-am33xx-beaglebone.img
> is going to be named MLO and put into the vfat boot partition or if I
> have something missing or done wrong, which is absolutely possible, of
> course!

The MLO files have mlo in their name.

> So, no *mlo* file.
> 
>> For your old setup, you will need two recipes. Just define your own
>> barebox.bb and barebox-pbl.bb recipes and inherit barebox in each and
>> use different configs. All the core logic is in a barebox.bbclass to
>> allow you to easily create your own recipes.
> 
> So only using this approach with two barebox.bb and barebox-pbl.bb I
> would get an additional *mlo* file, right?
> As said, if I can omit this approach this is fine by me.

Given that eMMC doesn't work yet for the approach with a single recipe,
I'd suggest you just add two recipes for now.

Cheers,
Ahmad

> 
> Regards
> Konsti
> 
> 
> 

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |