I try to run Android from SD-card. This card is prepared. There are partitions: boot(FAT32), rootfs(ext4), system(ext4), cache(ext4) and usedata(ext4). Boot partitions has files to run u-boot: MLO, u-boot.bin and uImage. To run it I use commands
mmcinit 0 fatload mmc 0 0x80000000 uImage setenv bootargs 'console=ttyO2,115200n8 <a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="dfb2bab2e2ebeae9929fefa7e7efefefefefefef">[email protected]</a> <a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="fc919991c1c9cdceb1bccc84bdcccccccccccccc">[email protected]</a> init=/init vram=10M omapfb.vram=0:4M androidboot.console=ttyO2 root=/dev/mmcblk1p2 rw rootwait rootfstype=ext4' bootm 0x80000000
Than I see how Linux starts. But after few seconds on step of loading rootfs I see an error message
[ 4.015655] EXT4-fs (mmcblk1p2): couldn't mount RDWR because of unsupported optional features (400) [ 4.036499] sd 0:0:0:0: [sda] Attached SCSI removable disk [ 4.079986] List of all partitions: [ 4.083801] b300 31162368 mmcblk0 driver: mmcblk [ 4.089660] b301 128 mmcblk0p1 f9f21f00-a8d4-5f0e-9746-594869aec34e [ 4.097839] b302 256 mmcblk0p2 f9f21f01-a8d4-5f0e-9746-594869aec34e [ 4.106018] b303 128 mmcblk0p3 f9f21f02-a8d4-5f0e-9746-594869aec34e [ 4.114288] b304 16384 mmcblk0p4 f9f21f03-a8d4-5f0e-9746-594869aec34e [ 4.122436] b305 16 mmcblk0p5 f9f21f04-a8d4-5f0e-9746-594869aec34e [ 4.130676] b306 8192 mmcblk0p6 f9f21f05-a8d4-5f0e-9746-594869aec34e [ 4.138916] b307 8192 mmcblk0p7 f9f21f06-a8d4-5f0e-9746-594869aec34e [ 4.147094] 103:00000 524288 mmcblk0p8 f9f21f07-a8d4-5f0e-9746-594869aec34e [ 4.155334] 103:00001 262144 mmcblk0p9 f9f21f08-a8d4-5f0e-9746-594869aec34e [ 4.163574] 103:00002 30342128 mmcblk0p10 f9f21f09-a8d4-5f0e-9746-594869aec34e [ 4.171874] b310 2048 mmcblk0boot1 (driver?) [ 4.177734] b308 2048 mmcblk0boot0 (driver?) [ 4.183593] b318 15179776 mmcblk1 driver: mmcblk [ 4.189453] b319 102400 mmcblk1p1 00000000-0000-0000-0000-000000000000 [ 4.197692] b31a 10240 mmcblk1p2 00000000-0000-0000-0000-000000000000 [ 4.205932] b31b 1 mmcblk1p3 00000000-0000-0000-0000-000000000000 [ 4.214141] b31d 262144 mmcblk1p5 00000000-0000-0000-0000-000000000000 [ 4.222351] b31e 13228032 mmcblk1p6 00000000-0000-0000-0000-000000000000 [ 4.230682] b31f 1572864 mmcblk1p7 00000000-0000-0000-0000-000000000000 [ 4.238891] No filesystem could mount root, tried: ext4 [ 4.244812] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,26) [ 4.254089] CPU1: stopping
I don’t know why it happens.
How can I solve this problem?
Answers:
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Method 1
The ext4 feature (400) is the new metadata_csum feature. If this feature is enabled and old tools are used to mount the filesystem they will only be able to mount read-only.
https://ext4.wiki.kernel.org/index.php/Ext4_Metadata_Checksums
To create a ext4 filesystem without this feature:
sudo mke2fs /dev/sdb1 -O ^metadata_csum
Or turn it off on an already created filesystem:
sudo tune2fs -O ^metadata_csum /dev/sdb1
Method 2
The error “EXT4-fs : couldn’t mount RDWR because of unsupported optional features (400)” is due to different versions between the partition formatter (mkfs.ext4) and the mounter.
You have two options:
a) Either you have to upgrade the mounter program using a newer distro inside the SD-card.
b) or you have to backup the files, reformat the SD-card with the same distro (the same ext4 versions) you are doing the mounting, and after the reformat copy the files again to the SD-card.
In the second option, care must be taken with the original ext4 options the formatter has put, trying to consider the same options at reformat. Note also that a reformat of partitions doesn’t need a repartition of the whole device, so the boot MBR would not be altered.
All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0