error when mounting md0 invalid argument

[David Christensen]

On 5/31/19 5:29 AM, David Mehler wrote:
> Hello,
> 
> I've got a copy of the FreeBSD 12.0 memstick img file. I'm trying to
> mount it to make some changes to allow it to go serial terminal by
> default. I'm doing:
> 
> mdconfig -a -t vnode -f path/to/img
> and have also added the -u0 option to that line as well.
> 
> An mdconfig -l does indeed show /dev/md0 and file -s /dev/md0 shows
> dos/mbr imgage  I believe that was. I then try:
> 
> mount /dev/md0 /mnt
> 
> and get invalid argument. Nothing in the logs. I've tried
> mount_msdosfs and mount_ufs same result invalid argument.
> 
> Any suggestions appreciated.
> 
> Thanks.
> Dave.

I wanted to make changes to:

     FreeBSD-11.2-RELEASE-amd64-memstick.img


I burned the image to a USB flash drive and then mounted it:

	2019-05-23 14:13:46 toor at ragnar ~
	# camcontrol devlist | grep -i sandisk
	<SanDisk SanDisk Cruzer 8.02>      at scbus5 target 0 lun 0 (da0,pass5)

	2019-05-23 14:16:27 toor at ragnar ~
	# gpart show -p da0
	=>      1  7913470    da0  MBR  (3.8G)
		1     1600  da0s1  !239  (800K)
	     1601  1505616  da0s2  freebsd  [active]  (735M)
	  1507217  6406254         - free -  (3.1G)

	2019-05-23 14:17:24 toor at ragnar ~
	# gpart show -p da0s2
	=>      0  1505616   da0s2  BSD  (735M)
		0       16          - free -  (8.0K)
	       16  1505600  da0s2a  freebsd-ufs  (735M)

	2019-05-23 14:17:53 toor at ragnar ~
	# mount /dev/da0s2a /mnt

	2019-05-23 14:18:04 toor at ragnar ~
	# mount | grep da0s2a
	/dev/da0s2a on /mnt (ufs, local)


The file system reads 100% full, but by working as root I can encroach 
into the reserved space and make changes to the BSD installer:

	2019-05-23 14:18:18 toor at ragnar ~
	# cd /mnt/usr/libexec/bsdinstall

	2019-05-23 14:19:58 toor at ragnar /mnt/usr/libexec/bsdinstall
	# vi zfsboot


If you have more than a little content to add, the proper way would be 
to start at the front end of whatever process creates the image.  (I 
haven't learn that, yet.)


David