External programming interfaces

6.10 LPAR mode

Applications can use the CHSC subchannel device driver through ioctls.

Programmers: This information is intended for programmers who want to program additional functions for the CHSC subchannel device driver.

Issue ioctls on the misc character device /dev/chsc to obtain information on the current I/O configuration and to dynamically change the I/O configuration. The ioctls and the structures that are passed are defined in the header file arch/s390/include/chsc.h.

To use an ioctl, for example CHSC_START, issue a call of the form:

rc = ioctl(fd, CHSC_START, <pointer to chsc_async_area>);

Table 1 lists the ioctls that are defined.

Table 1. The CHSC ioctls
Name	Structure passed	Description
CHSC_START	struct chsc_async_area	Use to start an asynchronous chsc request that changes the I/O configuration.
CHSC_INFO_CHANNEL_PATH	struct chsc_chp_cd	Use to obtain information about a specific channel path.
CHSC_INFO_CU	struct chsc_cu_cd	Use to obtain information about a specific control unit.
CHSC_INFO_SCH_CU	struct chsc_sch_cud	Use CHSC_INFO_SCH_CU to obtain information about control units on a subchannel.
CHSC_INFO_CI	struct chsc_conf_info	CHSC_INFO_CI can be used to obtain the configuration information as needed by the dynamic I/O configuration chscs.
CHSC_INFO_CCL	struct chsc_comp_list	CHSC_INFO_CCL can be used to obtain information about various configuration components.
CHSC_INFO_CPD	struct chsc_cpd_info	Use CHSC_INFO_CPD to obtain a description of a specified channel path.
CHSC_INFO_DCAL	struct chsc_dcal	Use CHSC_INFO_DCAL to obtain domain attributes of the configuration.
CHSC_START_SYNC	struct chsc_sync_area	Use CHSC_START_SYNC to start a synchronous chsc request.
CHSC_ON_CLOSE_SET	struct chsc_async_area	Install the asynchronous on close chsc request. This request is executed when the device node is closed.
CHSC_ON_CLOSE_REMOVE	none	Remove the asynchronous on close chsc request.