I have an idea for the old good devices like tl-mr3420 ( I have 3 ) , if I replace the 4 mega flash memory to 32m to use 8m as a boot flash and use the rest 24M as a swap partition is this give me performance near to the fixed memory , I know already I can solder a ram chip 64m instead the 32m but it is hard to me .
I have this already
spi has limited write cycles - if you use it as swap you'll reach the limit and destroy your flash
Besides the problem maurer mentioned (you will destroy your flash within days by using it for swap), these flash chips are also rather slow (that isn't much of an issue for the firmware itself, but it would be for swap).
SPI NOR chips larger than 16MB use a different addressing scheme (since 3 bytes = 2 ** 24 = 16M) and require different ROM and bootloader support for their 4 byte addresses.
So it is readily possible to expand the flash to 16M but not beyond that.
A pin compatible 64MB RAM chip exists. The RAM expansion requires no software changes and there is no loss of speed.
So upgrade flash to 16M and RAM to 64
@springtales Do not do that.
- this would decrease performance to unusable (use floppy disk as a swap for the similar performance)
- and finally destroy SPI flash.