Greetings,
I'm currently trying to access a memory block allocated using CMEM from within a kernel driver.
The setup is the following:
CMEM allocates memory block. Memory will be passed to the GPU using the eglCreateImageKHR. The GPU renders something into the memory block
and I want to transfer the result via GPMC to an FPGA.
Rendering works flawlessly. I can read out the results in the user-space application by using the pointer returned by CMEM_alloc.
But when I pass the physical address returned by CMEM_getPhys (0x87000000) to the driver I wrote for the FPGA communication, I got a kernel oops
telling me: Unable to handle kernel paging request at virtual address 87000000
So it seems, like the kernel driver is not able to directly access a physical address. I guess that's because you can only access addresses in kernel space, which is obviously not within the CMEM physical address space.
Now my question is, how can I access the memory where the rendered image is located, from within a kernel driver?
Is there something like map physical address to kernel space? I read about phys_to_virt but it seem like the physical address passed as argument has to be already within the kernel space, so a CMEM address probably won't work.
Any help is appreciated!
