> But my point is that you need to have a valid boot or valid not-boot on the eMMC.
No, the bootrom is looking for idbloader, the media and fstable is irrelevant,
and any partitions or filesystems on them,,,,,only the existence or absence of a media,,
because the bootrom is ONLY looking at specific locations for the idbloader signature
Uboot only enters the picture AFTER idbloader has activated the mb memory
(because the bootrom has very little memory)
The point is,,, all uboots are not equal, sometimes a uboot on emmc
is not compatible with a distro on SD (like the recent manjaro's)
If there is a uboot on emmc it will be ALWAYS used, since it is found first,
so if you write an image to emmc, you have a NEW uboot, and now that one will be always used
This might not work out, at the least you have not tested it (the uboot on SD)
No, the bootrom is looking for idbloader, the media and fstable is irrelevant,
and any partitions or filesystems on them,,,,,only the existence or absence of a media,,
because the bootrom is ONLY looking at specific locations for the idbloader signature
Uboot only enters the picture AFTER idbloader has activated the mb memory
(because the bootrom has very little memory)
The point is,,, all uboots are not equal, sometimes a uboot on emmc
is not compatible with a distro on SD (like the recent manjaro's)
If there is a uboot on emmc it will be ALWAYS used, since it is found first,
so if you write an image to emmc, you have a NEW uboot, and now that one will be always used
This might not work out, at the least you have not tested it (the uboot on SD)