Operator error. I was apparently using the wrong UART. See https://github.com/raspberrypi/linux/issues/3821.
** Bug watch added: github.com/raspberrypi/linux/issues #3821 https://github.com/raspberrypi/linux/issues/3821 ** Changed in: linux-raspi (Ubuntu Focal) Status: New => Invalid ** Changed in: linux-raspi (Ubuntu Groovy) Status: New => Invalid -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-raspi in Ubuntu. https://bugs.launchpad.net/bugs/1893189 Title: Pi 4B doesn't boot with 'earlycon=pl011,0xfe201000' Status in linux-raspi package in Ubuntu: Invalid Status in linux-raspi source package in Focal: Invalid Status in linux-raspi source package in Groovy: Invalid Bug description: After adding 'earlycon=pl011,0xfe201000' to cmdline.txt a Pi 4B no longer boots the 5.4 kernel. It's stuck at: MMC: mmcnr@7e300000: 1, emmc2@7e340000: 0 Loading Environment from FAT... *** Warning - bad CRC, using default environment In: serial Out: serial Err: serial Net: No ethernet found. starting USB... No working controllers found ## Info: input data size = 6 = 0x6 Hit any key to stop autoboot: 0 switch to partitions #0, OK mmc0 is current device Scanning mmc 0:1... Found U-Boot script /boot.scr 2569 bytes read in 17 ms (147.5 KiB/s) ## Executing script at 02400000 8390528 bytes read in 624 ms (12.8 MiB/s) Total of 1 halfword(s) were the same Decompressing kernel... Uncompressed size: 25907712 = 0x18B5200 29530646 bytes read in 2145 ms (13.1 MiB/s) Booting Ubuntu (with booti) from mmc 0:... ## Flattened Device Tree blob at 02600000 Booting using the fdt blob at 0x2600000 Using Device Tree in place at 0000000002600000, end 000000000260ea26 Starting kernel ... Works fine on Pi 3B and 3B+. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-raspi/+bug/1893189/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
