How to divide a memory space on DDR.

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Recently,I work with a FPGA+TX2 platform.FPGA is used to provide image data with PCIE,so I need a pyhsical memory to save data on TX2.I am wonder how to find a safe and idle physical memory,then I can give its address to FPGA.
My idea is :
1.As the system startup a piece of memory will divide which will not be used by other process after that.
2.After the system startup I can find a safe and idle memory.
However,I do not know how to realize these two methods and have no idea if these two methods can do that.

2

Please use DMA APIs https://www.kernel.org/doc/Documentation/DMA-API.txt to allocate memory in system memory to which your FPGA based PCIe end point can do read and writes.

3

Dear Chay1991,

You can reserve memory in the DTS using no-map attribute and provide the base address to FPGA. You have to make sure the memory chunk you require is contiguous. You can find available memory chunks in /proc/iomem.

Use command:

cat /proc/iomem | grep System