Specifications

5.3 The `video=vc:...' Argument
A number, or a range of numbers (e.g. video=vc:2−5) will specify the first, or the first and last frame
buffer virtual console(s). The use of this option also has the effect of setting the frame buffer console to not be
the default console.
6. Boot Arguments for SCSI Peripherals.
This section contains the descriptions of the boot args that are used for passing information about the installed
SCSI host adapters, and SCSI devices.
6.1 Arguments for Upper and Mid−level Drivers
The upper level drivers handle all things SCSI, regardless of whether they be disk, tape, or CD−ROM. The
mid level drivers handle things like disks, CD−ROMs and tapes without getting into low level host adapter
device driver specifics.
Maximum Probed LUNs (`max_scsi_luns=')
Each SCSI device can have a number of `sub−devices' contained within itself. The most common example is
any of the SCSI CD−ROMs that handle more than one disk at a time. Each CD is addressed as a `Logical Unit
Number' (LUN) of that particular device. But most devices, such as hard disks, tape drives and such are only
one device, and will be assigned to LUN zero.
The problem arises with single LUN devices with bad firmware. Some poorly designed SCSI devices (old and
unfortunately new) can not handle being probed for LUNs not equal to zero. They will respond by locking up,
and possibly taking the whole SCSI bus down with them.
The kernel has a configuration option that allows you to set the maximum number of probed LUNs. The
default is to only probe LUN zero, to avoid the problem described above.
To specify the number of probed LUNs at boot, one enters `max_scsi_luns=n' as a boot arg, where n is a
number between one and eight. To avoid problems as described above, one would use n=1 to avoid upsetting
such broken devices
SCSI Logging (`scsi_logging=')
Supplying a non−zero value to this boot argument turns on logging of all SCSI events (error, scan, mlqueue,
mlcomplete, llqueue, llcomplete, hlqueue, hlcomplete). Note that better control of which events are logged
can be obtained via the /proc/scsi/scsi interface if you aren't interested in the events that take place at
boot before the /proc/ filesystem is accessible.
Parameters for the SCSI Tape Driver (`st=')
Some boot time configuration of the SCSI tape driver can be achieved by using the following:
st=buf_size[,write_threshold[,max_bufs]]
The Linux BootPrompt−HowTo
5.3 The `video=vc:...' Argument 21