AUTOCONF(4) | NetBSD Kernel Interfaces Manual (VAX) | AUTOCONF(4) |
On the VAX, devices in NEXUS slots are normally noted, thus memory controllers, UNIBUS and MASSBUS adaptors. Devices which are not supported which are found in NEXUS slots are noted also. The Q-bus on the MICROVAX is configured in the same way as the UNIBUS.
MASSBUS devices are located by a very deterministic procedure since MASSBUS space is completely probe-able. If devices exist which are not configured they will be silently ignored; if devices exist of unsupported type they will be noted.
UNIBUS devices are located by probing to see if their control-status registers respond. If not, they are silently ignored. If the control status register responds but the device cannot be made to interrupt, a diagnostic warning will be printed on the console and the device will not be available to the system.
Normally, the system uses the disk from which it was loaded as the root filesystem. If that is not possible, a generic system will pick its root device as the “best” available device (MASSBUS disks are better than SMD UNIBUS disks are better than RK07s; the device must be drive 0 to be considered). If such a system is booted with the RB_ASKNAME option (see reboot(2)), then the name of the root device is read from the console terminal at boot time, and any available device may be used.
June 5, 1993 | NetBSD 5.99 |