GSRD v16.1 memmap support


I have been trying to use the memmap kernel command line parameter in uBoot to reserve a block of memory in the HPS DDR for the FPGA to write to.

My experience is that the memmap is being ignored by the kernel.
Is memmap supported in the GSRD v16.1 kernel?

If not, what is the recommended approach to allowing the FPGA to write into the HPS DDR space without crashing the Linux kernel??




I think you can use the reserved memory :


Thanks, yeah I had a go at that.

When adding a reserved_memory node into the device tree, should you then expect to see the reserve section of memory appear in /proc/iomem ?

Or do you have to associate it with a device driver.
I tried this but was unsure what to change in my driver to map the reserved memory?


mmap does not allocate. Just maps virtual address where application is running to physical ones so you can access from the application to the hardware in FPGA.
I am confused because you talk about the kernel as if you are running in Operating System but later you talk about uboot.
Maybe this answer is helpful to you: