How to directly access linux's RAM with FPGA on de10-nano

Hello, FJumaah.

we are student of the same lab.

We have modify the DE10_NANO_SoC_FB demonstration. I know the DDR3-RTL demonstration has the f2h-sdram access method,

but we want to access the f2h_sdram from FPGA directly with the LXDE desktop, so we use the DE10_NANO_SoC_FB demonstration to do,

And the f2h_sdram parameter is different between the DE10_NANO_SoC_FB and DDR3-RTL, so i don't know how to use ...

The Linux system use the top 512MB address (0x0 - 0x1fffffff) , and i want to use (0x20000000 - 0xffffffff) address locate through the f2h_sdram from FPGA.

This is our system contents of the Qsys.

We try to use two address_span_extender to control the sdram address range.

One is used limit the Linux system usage (0x0000_0000 - 0x1fff_ffff),

The linux system is working on the FPGA.

​

​

Another if use to access the (0x20000000 - 0xffff_ffff ) address

​

but when i access the second one, The linux system will crash, and the results is not correct.

We don't know how to access the f2h_sdram with the LXDE desktop ( DE10-NANO-SoC-FB)

Thank you for replying