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Re: Install on Orange Pi Plus eMMC work but no reboot

Le 06. 10. 16 à 21:29, Vagrant Cascadian a écrit :

I don't believe there is any code in debian-installer to install u-boot;
the installer did not install it. I don't believe there is any code
within all of Debian to install u-boot automatically (unless you count
SD image generation). It is at this point a manual process.
And this is the only missing operation still required to fully support Debian a board like the Orange Pi Plus. 




Installing u-boot from within the debian-installer can be a
rather dangerous operation on many systems which is why the
installer doesn't try to do that yet.  The problem is that u-boot
isn't only a bootloader like GRUB but more like a PC BIOS and
nobody would expect the debian-installer to flash BIOS-updates on
a PC ;-).  There are quite a number of systems where writing
u-boot to internal storage going wrong completely bricks the
system, i.e the system is electronics garbage afterwards. Most
sunxi-based systems still have a way to trigger SD boot or FEL
boot as a way to manually restore the firmware, but not all of
them do, and on many non-sunxi-platforms a broken u-boot write is
completely unrecoverable except by unsoldering the flash or - if
one is lucky - by accessing it via JTAG, but both are methods
that are inaccessible for a normal user.

I understand, but the SD card image of the Debian installer is
specifically targeted for the Orange Pi Plus board so it can take
advantage of it.

While the SD card images can be used for recovery in many cases, it is
also possible that u-boot installed to eMMC fails in such a way that it
doesn't fall back to SD card, requiring a lot of effort to reset the
board. It depends entirely on the boot ROM of the board what order it
searches for the bootloader...
Not on that board. The H3 processor chip integrate a boot ROM that always first look at the SD card and then at the eMMC (unless forced into the special FEL mode). There is no way to break the ROM integrated into the processor chip. Take a look at http://linux-sunxi.org/BROM for the details. 


Given that experience, I tend to strongly prefer installing u-boot on SD
card when possible, as you can easily remove the SD card and reinstall a
known-good u-boot from another machine.
This is exactly how the H3 boot ROM work already. You can write anything you want into the eMMC, there is absolutely no way to break the SD card boot from the CPU ROM. So there is no danger in writing the bootloader into the eMMC on that board. Writing the bootloader on the eMMC this is exactly what a user will expect while installing Debian into the eMMC. 




I'll put looking into support for installing u-boot from within
the installer at least on certain systems onto my (unfortunately
already way too long) todo list, but that will surely take quite
some time. I'm also CCing Vagrant Cascadian, the Debian u-boot
maintainer for some further input on this topic.

Basically, it will require much of the same code as upgrading u-boot:

   https://bugs.debian.org/812611

Which has been on my todo list for quite some time with little activity.
Due to the risk of bricking, both fresh installation and upgrading of
u-boot should probably require some sort of opt-in process.


Knowing how to install u-boot on a particular set of boards is another
feature that's needed, although the SD-card image generation in
debian-installer is a good start for several boards.


To make matters more complicated, there are definitely some boards
(Firefly, maybe BeagleBoard-X15) which can install the OS to eMMC, but
u-boot still has to be loaded from SD card. I don't think we have much
information on which boards those are. It may also vary from one u-boot
version to the next...


So, in short, there are quite a few complications to take into
consideration. If someone can propose patches that take into account all
these issues quite soon, it *might* be feasible for stretch.
From a user point of view this would be a major achievement for the Debian armhf port that finally make some ARM boards as easy to install than a regular PC. Well, maybe even easier than the actual UEFI PC... 

Regards,
Jean-Christian
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