Boot from usb, but initrd mount /dev/mmcblk2p2, rather than /dev/sda2

[0neday]

I flash your latest firmware openwrt_s905d_k5.4.171_2022.01.15.1130.img , and then plug into usb port.

I found, maybe boot from usb work, but Initrd ramdisk mount /dev/mmcblk2p2

root@OpenWrt:~# df -h
Filesystem                Size      Used Available Use% Mounted on
udev                    512.0K         0    512.0K   0% /dev
tmpfs                   181.0M    108.0K    180.9M   0% /run
/dev/mmcblk2p2          973.0M    199.5M    767.7M  21% /
tmpfs                   905.1M     84.0K    905.0M   0% /tmp
tmpfs                   512.0K         0    512.0K   0% /dev
/dev/mmcblk2p4            4.5G    161.6M      4.1G   4% /mnt

root@OpenWrt:/opt# uname  -a
Linux OpenWrt 5.4.171-flippy-69+o #366 SMP PREEMPT Tue Jan 11 23:58:30 CST 2022 aarch64 GNU/Linux

root@OpenWrt:/opt# ls /lib/modules/5.4.1
5.4.154/             5.4.170-meson64-dev/

root@OpenWrt:/opt# lsmod
gpio_keys_polled       16384  0

this show ramdisk init kernel and load drivers for hardware, and then mount rootfs is /dev/mmcblk2p2, rather than /dev/sda2 this so wierd!

I use this to extract initrd.img and check init script

maybe_break mount
log_begin_msg "Mounting root file system"
# Always load local and nfs (since these might be needed for /etc or
# /usr, irrespective of the boot script used to mount the rootfs).
. /scripts/local
. /scripts/nfs
. /scripts/${BOOT}
parse_numeric "${ROOT}"
maybe_break mountroot
mount_top
mount_premount
mountroot
log_end_msg

[ophub]

You are not booting from usb. The system is still booted from emmc.

Re-download the firmware, re-write the U-disk, insert the U-disk into the box, and then re-plug the power supply to boot from the U-disk.

What does extracting initrd.img do? Compile the kernel?

[0neday]

Re-download the firmware, re-write the U-disk, insert the U-disk into the box, and then re-plug the power supply to boot from the U-disk.

result is same.

What does extracting initrd.img do? Compile the kernel?

nop, kernel is not key, I dont care about kernel. I check why mount /dev/mmcblk2p2, rather than /dev/sda2？

cat /proc/cmdline get some bootargs,

BOOT=ROOTFS

from . /scripts/local , function local_mount_root is key function to mount rootfs

I dont know how initrd get rootfs uuid?

maybe I need a console to get into init ramdisk when system boot.

If I know how initrd get rootfs uuid, I will add a if else condition to boot rootfs from usb when detect /dev/sda devices, It is easy to realize in init script.

[ophub]

As long as boot from usb, sda is automatically mounted. Your current situation shows that you have not booted from usb, some n1 boxes choose a U disk, change a U disk, or change another socket, change the firmware.

[ophub]

But the firmware in the U disk is invalid.

Do you have a usb keyboard plugged in? Unplug it, insert the u disk into the socket near the hdmi

[0neday]

insert the u disk into the socket near the hdmi

yes

But the firmware in the U disk is invalid.

is valid, I confirm!

I can mount /dev/sda2 and /dev/sda1 on current system.

[ophub]

Your U disk is manually mounted for storage. The firmware in your USB flash drive is invalid, and the boot from the USB flash drive is not properly booted.

Change the U disk, change the firmware. Solve the function that the firmware in the U disk can boot normally.

[0neday]

@ophub use blkid get your firmware UUID of rootfs,

xx-pc@xx-virtual-machine:~/Desktop$ sudo blkid  /dev/loop3p2
/dev/loop3p2: LABEL="ROOTFS" UUID="b250e917-e0a6-4061-9145-b8ee0cc20fea" UUID_SUB="fdb0d788-5b35-4d1e-8619-75a37574ddba" TYPE="btrfs"

and then flush your firmware into usb, then change

sed -i "s/LABEL=ROOTFS/UUID=b250e917-e0a6-4061-9145-b8ee0cc20fea/" uEnv.txt

plug usb into N1 box, and boot successfully