Regression/kernel4.15

[tmagik]

Update uboot, linux, and uEnv.txt configs to work reliably together and with 'make format-boot-loader'

[jim-wilson]

I was able to boot this on my board at home. My board is plugged into a microsemi expansion board, and I was able to access pci devices on the board: a SATA drive, and a thumb drive attached to a USB card.

However, I see that you still haven't updated the toplevel README.md file. I consider this a fatal flaw.

1. It only booted because I know that a non-standard setting of the MSEL switches is required. I had to check the Unleashed Getting Started Guide for info, and managed to get it right on my second try. But this really needs to be documented if you expect anyone outside the inner circle to ever be able to use this. For the record, I had to move the second switch from the bottom (see page 8) to the right.

2. I see that you disabled the command that creates a filesystem on the second partition. I can see how this would be useful for firmware development, as you can try multiple u-boot revisions without clobbering your filesystem. But this will fail for naive users who will end up with no filesystem at all. This needs to be parameterized somehow so that the filesystem is created by default, and people who don't want it can avoid it, maybe by setting a special makefile variable. Or more complicated, ask a question and check the reply, but this is harder to write and maintain.

3. "make sim" is documented but doesn't work anymore. I'm OK with breaking this temporarily, and maybe even permanently to get u-boot, but it needs to be documented.

4. You have two git submodules pointing at your own private tmagik repos, but maybe this is temporary for the transition? We will need sifive/freedom-u-sdk using only sifive or riscv git submodules.

Non-fatal errors:

1. Not sure why the partition 4 exists for uboot-env, as it appears you are putting the uboot environment in partition 1 alongside the boot image.

2. New makefile uses mcopy. I wonder if that is part of a base OS install. We might need to update the dependencies list for that.

3. The root= on the bootargs line in uEnv.txt doesn't seem to work. It doesn't boot up with the second
   partition mounted. I thought maybe it didn't work because I don't have a linux system there, so I tried changing it to /dev/sda1 which has a full fc29 install on it, but that didn't work either. Maybe it is set up to always boot into busybox?

4. I made the mistake of hitting the keyboard once while u-boot was waiting for input, and things got confused. It looks like maybe I got a u-boot prompt, but I wasn't able to type character there and the stuff printed back looked like the wrong baud rate or something. But I don't care much about u-boot development, so I don't really need this to work now.

[tmagik]

Closing as dead development branch