Hi Oliver, Thanks a lot for your time and the answer. > Right, you turn on the MMU and the next time printk() is called the > console driver tries to write to 0xFF00_0000. That's not a valid > virtual address so it explodes. To make an address usable in both real > mode (i.e. pre-mmu) and virtual mode you need to have the page tables > setup so that virtual address maps to the same physical address. > Setting up that mapping is what early_ioremap() does. That's why > there's a warning telling you to use it. > > Based on the in-tree DTS files earlycon doesn't seem to be used on any > powerpc systems. My guess would be that most ppc platform use udbg > (very old, powerpc specific thing) rather than earlycon for this kind > of super-early debug output. Considering you're getting console output > via udbg I'd say just removing earlycon from your kernel command line > will probably fix your issue.
Well, I disabled all the early logs (now bootargs = “” in dts) and modified .config so that no earlycon.c gets compiled at all. The followings are the only compiled files within the `/derivers/tty/serial`: serial_base_bus.o, serial_core.o, serial_ctrl.o, serial_port.o, xilinx_uartps.o Now, I get no outputs during booting procedure which sounds normal, I guess. But still no luck getting to the rootfs or anywhere which actually initializes the `xilinx_uartps` driver and print something. Also please check shenki’s blogpost’s logs, if you have enough time: https://shenki.github.io/boot-linux-on-microwatt <https://shenki.github.io/boot-linux-on-microwatt> Based on the blog post, I think there should be no problem to get the early booting logs. Bests, Manili
