Re: Can't mount root partition after rebuilding kernel with DKWEDGE_METHOD_MBR

[Brad Spencer <brad%anduin.eldar.org@localhost>]

Pham Ngoc-Dung <ifa26417%outlook.com.vn@localhost> writes:

> Hi. On my hard drive (wd0, MBR), I have 3 partitions originally for Linux, including a boot partition (ext2 formatted), and another partition with NetBSD installed.
> For a reason I wanted to mount the Linux boot partition, which should have been easy since ext2 is supported by NBSD. But except fdisk where it showed up, I couldn't find it anywhere, nor a way to mount it.
> A little bit more of research, then I found out about dk(4). I tried to rebuild the kernel with DKWEDGE_METHOD_MBR uncommented. It did boot from that kernel, but it couldn't mount my root device, However the 3 Linux partitions were now detected: 
>
> [4.8364408] wd0 at atabus0 drive 0
> [4.8364408] wd0: <ST500LT012-9WS142>
> [4.9467467] dk0 at wd0: "wd0e"
> [4.9467467] dk1 at wd0: "wd0f"
> [4.9467467] dk2 at wd0: "wd0h"
> [5.0676107] boot device: wd0
> [5.0676107] root on wd0a dumps on wd0b
> [5.0676107] vfs_mountroot: can't open root device
> [5.0676107] cannot mount root, error = 16
> [5.0676107] root device (default wd0a): 
>
> Is there a workaround or a fix to this behavior?


You also want this -> DKWEDGE_METHOD_BSDLABEL as well as (or even
instead of) DKWEDGE_METHOD_MBR.  That cause a wedge to be added for each
disklabel entry which should the system to find your root filesystem.
It appears that with just DKWEDGE_METHOD_MBR the system didn't notice
where its root fs was at.  In fact, you may need to leave out
DKWEDGE_METHOD_MBR and just use DKWEDGE_METHOD_BSDLABEL if your
disklabel contains information about all of the native NetBSD
filesystems and the linux ones.

You will have to change everything in your /etc/fstab to use /dev/dkN
notation rather than /dev/wd0M notation, but that isn't too hard to do.





-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org