I am using a S25FL256S SPI Flash for boot-up code. The system boots-up fine from power-on, but fails to boot-up from a warm system reset. What could be wrong?
Most likely you are using a S25FL256S SPI Flash without a reset input. You may have changed the EXTADD-Bit in the Bank Address Register to access the flash with 4-byte addresses during runtime. During a reset, the SPI Flash remains in the 4-byte address mode and the system tries to boot with 3 byte addresses which won't work. Therefore, you need to use a version of the SPI flash with a Reset input pin.