Specifications

Device Driver Entry Points

Copies the contents of a device’s registers to an error message buffer or a

diagnostic buffer.

Speciﬁed in

Specify the name of the register-dumping routine in the regdmp argument of

the DDTAB macro. This macro places the address of the routine into DDT$L_

REGDUMP.

Called by

The system error-logging routines (ERL$DEVICERR, ERL$DEVICTMO, and

ERL$DEVICEATTN) and diagnostic buffer ﬁlling routine (IOC$DIAGBUFILL)

call the register-dumping routine.

Synchronization

The operating system calls a register-dumping routine at the same IPL at

which the driver called the system routine ERL$DEVICERR, ERL$DEVICTMO,

ERL$DEVICEATTN, or IOC$DIAGBUFILL. A register-dumping routine must not

change IPL.

Context

A register-dumping routine executes within the context of an interrupt service

routine or a driver fork process, using the kernel-mode stack. As a result, it can

only refer to those virtual addresses that reside in system (S0) space.

The register-dumping routine preserves the contents of all registers except R0

through R2. If it uses the stack, the register-dumping routine must restore

the stack before passing control to another routine, waiting for an interrupt, or

returning control to its caller.

Input

Location Contents

R0 Address of buffer into which a register-dumping

routine copies the contents of device registers

R4 Address of device’s CSR (if the driver invoked

the WFIKPCH macro to wait for an interrupt or

timeout)

R5 Address of UCB

Exit

The register-dumping routine issues an RSB instruction to return to its caller.

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