Can't mount root partition after rebuilding kernel with DKWEDGE_METHOD_MBR

[Pham Ngoc-Dung <ifa26417%outlook.com.vn@localhost>]

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?