OSMMsgSetInboundFrameSize(D3i2o)

OSMMsgSetInboundFrameSize -- request change in message frame size of inbound FIFO of an IOP

Synopsis

#include <sys/types.h>
#include <i2o/common.h>

int OSMMsgSetInboundFrameSize(int IopNum, int size, uint_t flags)

Description

OSMMsgSetInboundFrameSize requests a change in the message frame size of the inbound FIFO of IOP IopNum at the next reboot.

Arguments

IopNum: Global number of the the IOP.
size: Size in bytes of message frame requested. This must be a power of 2.
flags: The flag I2O_FRAMESIZE_FORCE forces the change. All other bits of the flag are reserved and should be set to zero.

Return values

SUCCESS: Message successfully sent to the IOP to change the size of the inbound message frame after the next reboot.
EINVAL: IOPNum is invalid, or size is not a power of 2.

Usage

The system keeps an internal variable which represents the message frame size that the IOP will use at the next reboot. Requests to lower the value of this variable are silently ignored and SUCCESS is returned unless the I2O_FRAME_FORCE flag is set.

For example, if the system will use 128-byte message frames, it sets the variable to 128 bytes. If OSM ``A'' sends OSMMsgSetInboundFrameSize(n, 512, 0), then the a message is sent to IOP n requesting the message frame size be 512 bytes on the next reboot. If the message is successful, the variable is set to 512 and SUCCESS is returned to the caller. If OSM ``B'' now sends OSMMsgSetInboundFrameSize(n, 256, 0), the system will simply return SUCCESS to the caller. OSM ``B'' can quite easily use the 512-byte message frame. If for some reason OSM ``B'' really does need to lower the size at the next reboot to 256 bytes, it must set the I2O_FRAME_FORCE flag. The system will then send the message. If the message is successful, the variable is updated and SUCCESS is returned.

Context and synchronization constraints

User or blockable context

Hardware applicability

All

Version applicability

i2omsg: in HDK Technical Reference 2

Differences between versions

None

References

Intro(D3i2o), OSMMsgGetInboundFrameSize(D3i2o), OSMMsgGetOutboundFrameSize(D3i2o)