Implementing Driver Gestalt

If a native driver has indicated support for driver gestalt, as described in the previous section, it must conform to these rules:

It must respond to all unsupported status csCode values with a statusErr value, and to all unsupported control csCode values with a controlErr value. This rule is the most important for drivers to follow after calling DriverGestaltOn.

It should be capable of closing properly and of removing vertical blanking (VBL) tasks, Time Manager tasks, drive queue elements, and so on. Drivers that can close should return noErr in response to Close requests. If it is absolutely not possible for the driver to close, it must respond with closErr and continue to function as if the Close request had not been issued.

It must implement the csCode values listed in Table 8-3 and described in the rest of this section. Driver clients seeing the DriverGestaltEnable bit set will assume that these calls will either produce the required actions or result in a statusErr or controlErr.

It must not use private csCodes with values lower than 128. All codes must be allocated withing the range 128 to 32767.

Note

The kcsDriverGestalt and kcsDriverConfigure codes produce the principal functionality of the native driver model. For historical reasons, setting the DriverGestaltEnable bit also requires that the other calls listed in Table 8-3 either be supported or return an error code. Future control or status calls for all native PCI drivers will be implemented using only selectors through DriverGestalt and DriverConfigure.

Table 8-3 Driver gestalt codes

Name	Value	Description
Status codes
`kcsDriverGestalt`	43	General status information
`kcsGetPowerMode`	70	Returns card power mode 1
`kcsReturnDeviceID`	120	Returns SCSI device ID in `csParam[0]`
Control codes
`kcsDriverConfigure`	43	General configuration commands
`kcsSetStartupDrive`	44	Designates partition as a boot partition
`kcsSetPowerMode`	70	Sets card power mode *

1. For a discussion of power modes, see Card Power Controls.