BSD Kernel Interfaces Manual
ahc — Adaptec VL/EISA/PCI SCSI host adapter driver
To compile this driver into the kernel, place the following lines in your kernel configuration file:
For one or more VL/EISA cards:
For one or more PCI cards:
To allow PCI adapters to use memory mapped I/O if enabled:
To configure one or more controllers to assume the target role:
options AHC_TMODE_ENABLE <bitmask of units>
Alternatively, to load the driver as a module at boot time, place the following lines in loader.conf(5):
This driver provides access to the SCSI bus(es) connected to the Adaptec AIC77xx and AIC78xx host adapter
Driver features include support for twin and wide busses, fast, ultra or ultra2 synchronous transfers depend-
ing on controller type, tagged queueing, SCB paging, and target mode.
Memory mapped I/O can be enabled for PCI devices with the “AHC_ALLOW_MEMIO” configuration option.
Memory mapped I/O is more efficient than the alternative, programmed I/O. Most PCI BIOSes will map
devices so that either technique for communicating with the card is available. In some cases, usually when
the PCI device is sitting behind a PCI->PCI bridge, the BIOS may fail to properly initialize the chip for
memory mapped I/O. The typical symptom of this problem is a system hang if memory mapped I/O is
attempted. Most modern motherboards perform the initialization correctly and work fine with this option
Individual controllers may be configured to operate in the target role through the “AHC_TMODE_ENABLE”
configuration option. The value assigned to this option should be a bitmap of all units where target mode is
desired. For example, a value of 0x25, would enable target mode on units 0, 2, and 5. A value of 0x8a
enables it for units 1, 3, and 7.
Per target configuration performed in the SCSI-Select menu, accessible at boot in non-EISA m