INTRO (9) NetBSD Kernel Developer's Manual INTRO (9) NAME ...

DMOVER (9) NetBSD Kernel Developer’s Manual DMOVER (9)void dmover_request_free(struct dmover_request ∗req)The dmover_request_free() function frees a dmover request structure. If the dmover functionrequires input buffers, and the input buffer descriptors associated with req were allocated bydmover_request_alloc(), then the input buffer descriptors will also be freed.void dmover_process(struct dmover_request ∗req)The dmover_process() function submits the dmover request req for processing. The call-backspecified by the request is invoked when processing is complete.The dmover_session_create() and dmover_session_destroy() functions must not be calledfrom interrupt context.The dmover_request_alloc(), dmover_request_free(), and dmover_process() functionsmay be called from interrupt handlers at levels IPL_VM, IPL_SOFTCLOCK, and IPL_SOFTNET, orinnoninterruptcontext.The request completion call-back is called from a software interrupt handler at IPL_SOFTCLOCK.BACK-END INTERFACEAback-end describes the dmover functions it can perform using an array of dmover_algdesc structures:struct dmover_algdesc {const char ∗dad_name; /∗ algorithm name ∗/void ∗dad_data; /∗ opaque algorithm description ∗/int dad_ninputs; /∗ number of inputs ∗/};The dad_name member points to a valid dmover function name which the client may specify.dad_data member points to a back-end-specific description of the algorithm.Aback-end presents itself to the dmover facility using the dmover_backend structure. The back-endmust initialize the following members of the structure:const char ∗dmb_nameThis is the name of the back-end.u_int dmb_speedThis is an estimate of the number of kilobytes/second that the back-end can process.void ∗dmb_cookieThis is a pointer to back-end private data.const struct dmover_algdesc ∗dmb_algdescsThis points to an array of dmover_algdesc structures which describe the functions the data movercan perform.int dmb_nalgdescsThis is the number of elements in the dmb_algdescs array.void (∗dmb_process)(struct dmover_backend ∗)This is the entry point to the back-end used to process requests.When invoked bythe dmover facility, the back-end’s (∗dmb_process)() function should examine thepending request queue in its dmover_backend structure:TheNetBSD 3.0 December 4, 2007 5