README for mly nophys patch
Doug White <dwhite@freebsd.org>

NOTICE: THIS PATCH HAS NOT BEEN TESTED IN A PRODUCTION ENVIRONMENT.
IT MAY CAUSE DATA LOSS, HAIR LOSS, IRRITABILITY, AND GENERL HYSTERIA.
DO NOT USE WITHOUT CONSULTING A DOCTOR.

This patch is an attempt to keep the system from squashing any
SAF-TE enclosure controllers attached to a Mylex mly-supported
device.  In the default driver, a passthrough allows direct access
to disks not attached to an array. Unfortunately, the Mylex card
does not provide a way of identifying what is a disk and what
is a SAF-TE controller. The Mylex controller depends on the SAF-TE
functionality to learn when disks have been replaced following a 
failure.  If CAM attempts to access these devices, it causes
them to lock up, and the auto-rebuild functionality is lost.
This causes the "mly0: enclosure target 0:11 device 0 offline" 
and "mly0: physical device 0:11 offline" messages to appear on boot.

This patch disables the passthrough by inhibiting the detection
of any physical devices attached to the Mylex. Since the Mylex
BIOS and Linux driver don't support passthrough anyway, I don't
feel this is a big loss of functionality.  I plan to continue
to discover a cleaner, finer-grained way of only turning off
the SAF-TE controllers and leaving the other devices untouched,
but comments on the -scsi mailing list don't give me much confidence,
and I'm working without specifications.  Hopefully there is a way to
obtain the Mylex's own probe information before running our own.

Note that the #define that controls the feature is inline with the
code, called DW_MLY_DISABLE_PHYS.  Commenting out the #define
will revert to the standard functionality.

Please email me with any comments. Thanks!