I've tested a simple split image build with newt and I can load both images and
have the bootloader boot the loader and then the loader boot and verify the
split image.
The loader application has a special call to loader_go that checks to see if
its meant to run a split app or not.
The main application has only one special piece (its #ifdef'd deep inside the
startup code automatically) where it re-copies and zeros the loader bss and
data sections before running. Of course the main app uses a different linker
script which as a few differences.
I have not yet implemented the extra hash check to ensure they match,but first
I wanted to get some configuration in so that the loader could decide whether
to boot the split image or not.
So now, I will implement configuration:
As part of newtmgr, Right now we have
list Show target images
upload Upload image to target
boot Which image to boot
fileupload Upload file to target
filedownload Download file from target
Currently the way we have it with split images, they are not bootable. So the
boot command will fail to boot an split image in the second partition and will
never copy a split image to the primary partition.
So we need an extra command to tell the loader whether to run the app or not.
We can't just erase the second partition anymore because the app is running
from it.
split_app Sets a flag to enable the split application
This flag would be ignored by normal dual images. If course if the flag was
set but the image was invalid, it will still not boot the app and will just run
the loader.
So an upgrade would look like this
1. you are happily running a split app
2. You set "split_app" to zero and reboot
3. The loader comes up and you upload a new loader
4. You set the boot to boot the new loader
5. You upload a new split app
6. You set the split_app to 1 and reboot
7. Everything is happy
Please provide comments on this. Unlike the design which largely hides details
to users, this UI will show up for everyone and they will have to understand.
Paul
