Hi,
On 25/10/17 10:42, Maxime Ripard wrote:
On Tue, Oct 24, 2017 at 06:21:43PM +0100, Andre Przywara wrote:
That being said I have prepared a patch to switch sunxi ARM64 boards over to ENV_IS_IN_FAT, because I guess we will hit the wall soon there and have no Thumb2 to get off lightly. And I believe that the arm64 boards mostly use a standardized way of booting, also are much less wide spread, so the number of affected users is probably less there.
I am just thinking of whether it's worthwhile to have some transition code, which tries multiple environment locations (first FAT, then MMC, for instance), or even contains code to migrate from one to another.
I started to look into the latter as well, because that's really what I'd like to see (for some time at least).
I guess having a custom environment handling method would be the best, and it doesn't seem that hard.
The behaviour I had in mind would be, when reading:
- Look for an environment in a FAT partition
- If not:
- Load the raw environment
- Print a warning
When writing:
- Try to write the environment to a FAT partition
- If it fails:
- Write to the raw environment
- Print a warning
That way, we can slowly migrate users in a transparent manner as soon as they would use saveenv, and we also provide a warning that things might (and actually will) break in the future if the setup isn't changed.
That was exactly what I had in mind as well!
Do you have some spare cycles to implement this? If not, I can give it a try.
We could even just rely on the existing methods from both standards environment code, we just need to make the functions !static.
There is even a Delphic comment in env/Kconfig: "At *present* the environment can be stored in only one place." ;-)
Cheers, Andre.
P.S. I will arrive tonight in Prague, for the DT workshop tomorrow.