Hi, I have been trying to port Vim4 to Mainline for the past few weeks. Downstream branch: https://github.com/khadas/linux/tree/khadas-vims-5.4.y - First approach: The compatible string way In that 5.4 branches, clean the device tree to the bare minimum to have a serial console, sd-card mount and ethernet, and reduce the kernel config to only build the necessary modules. With those 2 in hand (minimum dts and config), I could port the necessary drivers for which the dts have compatible strings. I did manage to boot once a v6.3 kernel with that dts and config. But it would hang a few seconds after booting the kernel. And after a few days of trying to debug the problem without success, I decided to move to another approach. - Second approach: The fat patch I compared a clean 5.4 branch and khadas 5.4 branch and generated a big fat patch with around 2.5 million lines, where when applied to clean 5.4, it would boot and work. I started to chop the fat patch to remove stuff that did not need to get vim4 working with only serial, ethernet and sd-card. I managed to reduce to 1.3 million lines the fat patch, but after that, things started to hang and crash, so I was unable to move on. At this point, I realized that 5.4 khadas was actually an Android12-5.4 branch with amlogic and khadas stuff. - Thrid approch: The android fat patch I am doing the same thing as the second approach but using an android12-5.4-lts branch as the start, where the comparison shows me only the amlogic and khadas changes made. I am still going through this method, but it is promising. Right now, I have the fat patch with 0.9 million lines. My idea here is that when that fat patch becomes small enough, I can apply it to a clean 5.4 (no Android) to work it out more. And when that patch becomes something tinny, I could apply it on mainline, adjusting for the kernel version jump. - Fourth approach: The rebase way (On hold) I could compare the android12-5.4-lts git log with the khandas-5.4 log and start to cherry-pick patches to a clean 5.4 (no Android), but from experience, I think that's going to take forever, and it would be very hard to apply patches as they refer to an Android branch, not mainline. The intermediate goal is to have a patch on top of the mainline that boots vim4, no matter how ugly. With that in hand, I can start re-structuring and getting ready for upstream. Now my question for the community: Is there a better way to port a board to the mainline when you only have an old kernel that boots? Thanks Lucas Tanure _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
