USB virtual media not useable

[Adrian Penisoara]

Most of the commercial/datacenter servers make use of virtual KVM and Drives instead of relying on physical devices. These devices are usually connected via the USB bus.

Latest versions of FreeBSD are unable to boot and/or install from ISO images mounted through virtual CDROM drives:
 * FreeBSD 9/10 are unable to properly detect the root filesystem to mount from the ISO image
 * FreeBSD 8 is able to mount the root filesystem, but unable to automatically detect the CD (ISO image) to make an installation; even after disconnect/reconnect operations / forcing re-discovery of the devices, it is still unable to read from the CD image

Such devices are usually USB connected and visible through the umass controller and attached as SCSI devices (cd0/cd1).

Sample kernel messages for an HP ProLiant DL380G7, 2 CPU/QC-32GB, System BIOS P67 (05/05/2011):

== FreeBSD 8.2/amd64 ==
ugen5.2: <HPI> at usbus5
umass0: <HPI Virtual Management Device, class 0/0, rev 2.00/0.01, addr 2> on usbus5
umass0: 8070i (ATAPI) over Bulk-Only; quirks = 0x0000
umass0:4:0:-1: Attached to scbus4

cd0 at umass-sim0 bus 0 scbus4 target 0 lun 0
cd0: <HP Virtual DVD-ROM \0000.0> Removable CD-ROM SCSI-0 device
cd0: 40.000MB/s transfers
cd0: cd present [353577 x 2048 byte records]
(cd0:umass-sim0:0:0:0): AutoSense failed
(cd0:umass-sim0:0:0:0): AutoSense failed
g_vfs_done():acd0[READ(offset=32768, length=2048)]error = 5

g_vfs_done():cd0[READ(offset=32768, length=2048)]error = 6

== FreeBSD 9.0/amd64 ==
ugen5.2: <HPI> at usbus5
umass0: <HPI Virtual Management Device, class 0/0, rev 2.00/0.01, addr 2> on usbus5
umass0: 8070i (ATAPI) over Bulk-Only; quirks = 0x0100
umass0:6:0:-1: Attached to scbus6

cd1 at umass-sim0 bus 0 scbus6 target 0 lun 0
cd1: <HP Virtual DVD-ROM \0000.0> Removable CD-ROM SCSI-0 device
cd1: 40.000MB/s transfers
cd1: cd present [313373 x 2048 byte records]
(cd1:umass-sim0:0:0:0): AutoSense failed

Trying to mount root from cd9660:/dev/is09660/FREEBSD_INSTALL [ro]...
mountroot: waiting for device cd9660:/dev/is09660/FREEBSD_INSTALL ...
Mounting from cd9660:/dev/is09660/FREEBSD_INSTALL failed with error 19.

mountroot> cd9660:/dev/cd1
Trying to mount root from cd9660:/dev/cd1 [] ...
g_vfs_done():cd1[READ(offset=32768, length=2048)]error = 6
Mounting from cd9660:/dev/cd1 failed with error 6