labs: bbb: drop warning about U-Boot flashed by SD-card being outdated

[tleb]

This warning is false since 054b2ff ("lab-data:bbb-recovery: align sdcard u-boot.img.final to snagboot's"):

Micro sd card recovery flash an old u-boot (u-boot.img.final, v2018.05)
on the eMMC. Bump u-boot.final to align it with u-boot used by snagboot
recovery.

We still keep the bold "(recommended)" string for the snagboot procedure in the document's introduction section.

A trainee was facing issues with snagboot (missing udev rules) and indicated being hesitant on trying this alternative approach. Trying the SD-card method might have unlocked him and allowed him to move forward in the kernel training labs.

[tleb]

Just to clarify: I created this pull request to ask for feedback rather than push directly. I am not certain everyone agrees with the change (even though I don't see many cons to it).

[miquelraynal]

Fine by me

[miquelraynal]

Just an FYI, there is one thing bothering me with this procedure, which is the fact that we push people for using recent/up-to-date components. IIRC the U-Boot used in this SD card is very old. The one we actually flash is more recent, I think we updated it recently though, so what people will see (ie. up to date components) is fine.

[tpetazzoni]

Just an FYI, there is one thing bothering me with this procedure, which is the fact that we push people for using recent/up-to-date components. IIRC the U-Boot used in this SD card is very old. The one we actually flash is more recent, I think we updated it recently though, so what people will see (ie. up to date components) is fine.

But that's quite unrelated, right? The SD card flashing procedure should also work to flash a modern U-Boot, right?

[miquelraynal]

It's not unrelated, we also share all the materials to build the flashing SD card, which is based on very old software.
And initially it was the same U-Boot compiled twice (with a slightly different configuration) that was used. This got decoupled recently.