The NOR FLASH library is an optional part of eCos, and is only applicable to some platforms.
The eCos NOR FLASH library provides the following functionality:
Identifying installed device of a FLASH family.
Read, erasing and writing to FLASH blocks.
Validating an address is within the FLASH.
Determining the number and size of FLASH blocks.
There are two APIs with the flash library. The old API is retained for backwards compatibility reasons, but should slowly be replaced with the new API which is much more flexible and does not pollute the name space as much.
FLASH devices cannot be read from when an erase or write
operation is active. This means it is not possible to execute code
from flash while an erase or write operation is active. It is possible
to use the library when the executable image is resident in FLASH. The
low level drivers are written such that the linker places the
functions that actually manipulate the flash into RAM. However the
library may not be interrupt safe. An interrupt must not cause
execution of code that is resident in FLASH. This may be the image
itself, or RedBoot. In some configurations of eCos, ^C on the serial
port or debugging via Ethernet may cause an interrupt handler to call
RedBoot. If RedBoot is resident in FLASH this will cause a crash.
Similarly, if another thread invokes a virtual vector function to
access RedBoot, eg to perform a
crash could result.
Thus with a ROM based image or a ROM based Redboot it is recommended to disable interrupts while erasing or programming flash. Using both a ROMRAM or RAM images and a ROMRAM or RAM RedBoot are safe and there is no need to disable interrupts.