# ext4 as root partition fails to mount

## sirlark

Hi,

I have a boot partition (ext3) and a root partition (ext4) and a kernel with ext4fs compiled in (not a module). The kernel is a copy from m old hdd (I just upgraded, which had an ext3 root partition. I could mount ext4 partitions using that kernel, and all the same userspace utils, but when my root partition is ext4 my kernel loads (i.e. GRUB is working happily) but fails to mount my root partition, complaining that I need to upgrade my mount utils/executable to handle ext4. What's up?

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## razixx

Did you do this yet?  

```

emerge -au e2fsprogs

```

Here's a really good page on ext4 and gentoo

[url]

http://en.gentoo-wiki.com/wiki/Ext4

[/url]

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## sirlark

yup ... both e2fsprogs and e2fsprogs-libs are emerged, and up to date. I can mount ext4 partitions, just not as the root partition

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## mv

Try passing the kernel parameter rootfstype=ext4

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## sirlark

rootfstype=ext4 made no difference

Maybe there's something wrong with my whole process in general.

I have a laptop with a single SATA drive 0f 80Gb with three paritions boot(ext3), swap and root(ext4). I have an external USB SATA drive of 250Gb. I wish to upgrade the laptops space. So I partitioned the 250Gb drive over USB to have boot (ext3), swap, and root (ext4) partitions. I tested that I could mount the ext 4 partition with the kernel from my current laptop installation, no problems. I mounted the internal 80Gb root partition independently in /mnt/temp (so I could copy without the devices and proc stuff), mounted the USB root partition, and copied over, did the same for the respective boot partitions. I grubbed the USB's boto partition, then I edited the fstab on the USB root partition accordingly, and swapped the drives out physically.

Have I missed something here? The same kernel could boot an ext4 root partition without issues from the 80Gb. What's changed? Grub finds the kernel, so grub worked... but the kernel refuses to mount the root partition as ext4.

The only difference I can think of is the on the old 80Gb, I made the root partition as ext3 and then used tunefs to upgrade it to ext4. Whereas the new HDD has been ext4 from the start.

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