Created attachment 249398 [details] dmesg from working boot i have two RPi4s, one 2GB and one 4GB, using SanDisk 16GB SD cards: mmc0: <MMC/SD bus> on sdhci_bcm0 mmc1: <MMC/SD bus> on sdhci_bcm1 mmc0: No compatible cards found on bus mmcsd0: 16GB <SDHC SC16G 8.0 SN 4D52ABA7 MFG 05/2022 by 3 SD> at mmc1 50.0MHz/4bit/65535-block these are both running 15.0 as of 312a05c39e5fd79b37ee6f922462232797f56a2a. i tested with both the current sysutils/rpi-firmware from ports (20230405), and the firmware from the current 15.0 binary snapshots. when booting with GENERIC, both RPis work fine. when booting with GENERIC-NODEBUG, the SD card won't attach and mountroot fails. this is reproducible. the problem appears to be specific to mmc, because if i put the SD card into a USB card reader instead, both systems boot fine with either kernel. i don't have an easy way to access dmesg on a failed boot, but i did notice it printed the error "DMA error 4 on CH5", relating to the mmc controller. full dmesg from one of the systems on a working boot is attached.
Created attachment 249402 [details] dmesg from GENERIC-MMCCAM tested with MMCCAM: - GENERIC-MMCCAM works - GENERIC-MMCCAM-NODEBUG hangs during kernel boot after probing sdda0 attached a dmesg from working GENERIC-MMCCAM system.
some additional testing: - i created a custom non-debug, modular kernel (no WITNESS or INVARIANTS) - this kernel booted fine on the 4GB system - however on the 2GB system the problem appears with this kernel this kernel is running a couple of local patches to build some drivers (genet, bcm_xhci, nvme) as modules, which probably isn't related to this issue. so i don't see any obvious cause here (kevens suspected it might be timing-related), but by next week i should be able to hook up a serial console and get a boot log from a failed boot.