How write fpga firmware with kernel version 4.18 / 4.19?

Linux Kernel
1

hi,
we use the kernel v4.15 and write the fpga firmware with the overlay devicetree,
this works great.
i want to try the new kernel version 4.18 but the folder
/sys/kernel/config/device-tree/
is missing.

have someone test 4.18 or 4.19 with devicetree (device-tree) overlay, and writing the fpga firmware?

thanks

2

Hi,
I have just experienced the same problem. Has anyone got any clue in the meantime how to solve this issue with 4.18/4.19 kernel?

3

Hello @hkhauke,
could I ask You if Your Linux kernel is properly configured to possess a support for device-tree overlay?
I has not got experience with Linux kernel version 4.18, but previous versions behave in such way that there is not necessary folders without DeviceTree overlay support configured.
Moreover, DeviceTree overlay should be applied (according to its documentation) to fseudo-filesystem /config/ rather than /sys/kernel/config/device-tree/. Of course, this pseudo-filesystem has to be configured too.
Besh wishes,
Jan Konečný.

4

Hi,

thank you for your response. I think that I figured out the problem in the meantime - please, correct me if I am wrong:

It seems that reconfiguring the system using device tree overlays is only supported by the Altera kernels. The 4.18 kernel I struggled with was the yocto-rt mainline kernel whereas the 4.9.76 kernel I finally chose to inject my device tree is the Altera kernel. I was not able to find out how the mainline kernel supports device tree overlays and the most likely solution is that it simply does not.

Best regards

Hauke