Hello all,
mm, i finally clarified the mistery: it is related to the flash 2Mx16 SST 29VF3201B i have chosed.
Unfortunately, even if the pinout is exactly as a correspondent size AMD x16 flash, i discovered that SST flash don't suport the x8 mode, or better, don't have the BYTE# signal on pin 47, but it is a NC.
I choosed SST for good pricing, and would avoid to replace it, so i am going to try to modify the colilo bootloader to copy rodata to rom.
Anyway this is just a beginner erro i guess 
Hope this can help soem other,
greetings,
angelo