[avr-gcc-list] Avoiding the flash temporary page buffer auto-erase

[Shaun Jackman]

> From the AVR data-sheet:

        The temporary buffer will auto-erase after a Page Write operation
        or by writing the RWWSRE bit in SPMCSR.

Is it possible to avoid this RWWSRE auto-erase behaviour. I'd like to
be able to partly fill up the temporary page buffer, jump to
application memory to do some processing, and then jump back to the
bootloader memory and complete filling up the temporary page buffer
and start the page write operation.

I did just this, and it seemed to mostly work, except that I call
boot_rww_enable() to set the RWWSRE bit and clear the RWWSB bit before
jumping to application memory. Unfortunately, setting the RWWSRE bit
clear the temporary page buffer, for some reason unknown to me.

Is it strictly necessary to set the RWWSRE bit before jumping to
application memory? What will happen if I do not? Elsewhere in the
datasheet it says...

        The RWWSB bit will be cleared if the RWWSRE bit is written to one
        after a Self-programming operation is completed. Alternatively
        the RWWSB bit will automatically be cleared if a page load
        operation is initiated.

What exactly is a page-load operation? Can I use this to clear RWWSB
bit without writing the RWWSRE bit and clearing the temporary page
buffer?

Thanks,
Shaun