blspec

blspec

[Alexander Shiyan]

Hello All.

Can anyone explain how to use the built-in blspec support?
I would like to try setting up booting via exlinux.conf...

Thanks!

Re: blspec

[Ahmad Fatoum]

Hello Alexander,

On 4/10/26 4:02 PM, Alexander Shiyan wrote:
> Hello All.
> 
> Can anyone explain how to use the built-in blspec support?
> I would like to try setting up booting via exlinux.conf...

exlinux.conf and bootloader spec are different formats.

Here's a bootloader spec example:

  $ cat /loader/entries/imx8mp-evk.conf
  title           PTXdist - Pengutronix-DistroKit imx8mp-evk
  version         6.18
  options         rootwait
  linux           /boot/Image
  devicetree      /boot/imx8mp-evk.dtb
  linux-appendroot        true


You can have multiple files under /loader/entries and barebox will
iterate over them, extract the compatible of the referenced devicetree,
compare it against its own and then decide what to boot.

The linux-appendroot key is barebox-specific and means barebox should
fixup root= according to the device it found the bootloader spec file
on. This is useful for the case where the bootloader spec files are
directly in the rootfs and not in a separate partition.

Cheers,
Ahmad



> 
> Thanks!
> 
> 

-- 
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: blspec

[Alexander Shiyan]

Hello Ahmad.

Is it possible to implement a similar provider that parses extlinux.conf
(i.e. finds DEFAULT, reads the corresponding LABEL section, extracts
KERNEL, INITRD, APPEND) and creates boot records based on it?

Thanks!

пн, 13 апр. 2026 г. в 17:01, Ahmad Fatoum <a.fatoum@pengutronix.de>:
>
> Hello Alexander,
>
> On 4/10/26 4:02 PM, Alexander Shiyan wrote:
> > Hello All.
> >
> > Can anyone explain how to use the built-in blspec support?
> > I would like to try setting up booting via exlinux.conf...
>
> exlinux.conf and bootloader spec are different formats.
>
> Here's a bootloader spec example:
>
>   $ cat /loader/entries/imx8mp-evk.conf
>   title           PTXdist - Pengutronix-DistroKit imx8mp-evk
>   version         6.18
>   options         rootwait
>   linux           /boot/Image
>   devicetree      /boot/imx8mp-evk.dtb
>   linux-appendroot        true
>
>
> You can have multiple files under /loader/entries and barebox will
> iterate over them, extract the compatible of the referenced devicetree,
> compare it against its own and then decide what to boot.
>
> The linux-appendroot key is barebox-specific and means barebox should
> fixup root= according to the device it found the bootloader spec file
> on. This is useful for the case where the bootloader spec files are
> directly in the rootfs and not in a separate partition.
>
> Cheers,
> Ahmad
>
>
>
> >
> > Thanks!
> >
> >
>
> --
> 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: blspec

[Ahmad Fatoum]

Hello,

On 4/13/26 21:15, Alexander Shiyan wrote:
> Hello Ahmad.
> 
> Is it possible to implement a similar provider that parses extlinux.conf
> (i.e. finds DEFAULT, reads the corresponding LABEL section, extracts
> KERNEL, INITRD, APPEND) and creates boot records based on it?

Sure, you can implement a custom `struct bootscanner` and do whatever
you like.

We already have a driver handling the U-Boot environment, so I don't see
why an optional extlinux.conf parser shouldn't be appropriate for upstream
if someone contributes it.

Cheers,
Ahmad

> 
> Thanks!
> 
> пн, 13 апр. 2026 г. в 17:01, Ahmad Fatoum <a.fatoum@pengutronix.de>:
>>
>> Hello Alexander,
>>
>> On 4/10/26 4:02 PM, Alexander Shiyan wrote:
>>> Hello All.
>>>
>>> Can anyone explain how to use the built-in blspec support?
>>> I would like to try setting up booting via exlinux.conf...
>>
>> exlinux.conf and bootloader spec are different formats.
>>
>> Here's a bootloader spec example:
>>
>>   $ cat /loader/entries/imx8mp-evk.conf
>>   title           PTXdist - Pengutronix-DistroKit imx8mp-evk
>>   version         6.18
>>   options         rootwait
>>   linux           /boot/Image
>>   devicetree      /boot/imx8mp-evk.dtb
>>   linux-appendroot        true
>>
>>
>> You can have multiple files under /loader/entries and barebox will
>> iterate over them, extract the compatible of the referenced devicetree,
>> compare it against its own and then decide what to boot.
>>
>> The linux-appendroot key is barebox-specific and means barebox should
>> fixup root= according to the device it found the bootloader spec file
>> on. This is useful for the case where the bootloader spec files are
>> directly in the rootfs and not in a separate partition.
>>
>> Cheers,
>> Ahmad
>>
>>
>>
>>>
>>> Thanks!
>>>
>>>
>>
>> --
>> 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 |
>>
> 


-- 
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 |