As I write at the below page, I found how to initialize 64 bits of Ram memory.
But my customer wants to initialize only 1 byte of Ram memory.
As far as I know, it is impossible because the e_stmw is the only one instruction I can use to initialize the Ram.
Is there a way to initialize only 1 byte of Ram memory ?
I think you have answered yourself. "Less than 64-bit write" consists of read-modify-write sequence. If you have uninitialized 64-bit data word, write to any smaller portion of this word performs read-modify-write, and the read will cause ECC error exception (IVOR1 - machine check).
Initialization must be done by 64-writes, there is no other option. ECC error free data then can be accesses by less than 64-bit accesses, of course.