LPC17xx:  Prioritized interrupts are not supported (although hooks are present to prioritize interrupts).  Make LPC17 Ethernet default priority to be the system default, not the highest.  If the unsupported feature is enabled, then at least it should do no harm

LPC17xx, TIVA, and Kinetis interrupt initialization:  use the NVIC ICTR register to determine how many interrupt lines/registers are supported by the MCU

Move the un-definitions of __ramfuncs__ from the sam_clockconfig.c to the common up_internal.h header file so that the attribute will be applied the same to function definitions and prototypes.

SAMA5 TWI: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 SSC: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 EMAC/GMAC: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 CAN: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 ADC: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

examples/touchscreen:  Add a configuration option to indicate that there is or is not an architecture-specific initialization function