2016-08-04 14:40 GMT+09:00 Wolfgang Denk wd@denx.de:
Dear James,
In message d18f75c7-388b-b607-ed70-64a250320d5a@gmail.com you wrote:
In your case, you could save the "erase" by overwriting the first 4 bytes (where the CRC32 checksum is stored) with 0xFFFFFFFF.
Wrong. I meant writing 0x00000000 - as you can always write that, setting any remaining 1 bits to 0 which does not require an erase of the sector.
In the case of my NOR flash storage, telling erase to do one byte actually causes the erasure of an entire flash sector, which we've reserved for the NV environment. You are of course correct that overwriting the CRC will have the same operational effect.
...and as the next "saveenv" will start with an erase, writing 0 to the CRC 32 field saves you one erase cycle on that sector.
I know, this is nitpicking. Soryy.
It's a rare occurrence that we need to do this, we don't use this sort of operation as a normal part of doing business.
Agreed. This should never be part of regular operation.
Best regards,
Wolfgang Denk
Sorry for my late reply.
I was in the conflict between my coworkers from different schools.
One always wants to save his preference in the environments in a non-volatile device.
Another wants to load "uEnv.txt" to adjust environments, so the environments from a non-volatile device are just annoying for him. He just want to clean the saved environments away, and makes the sectors for environments to the initial state.
I was searching a way to make everyone happy. As Tom pointed out, the latter can use CONFIG_ENV_IS_NOWHERE. Thanks!