Screen Version

School of Computer Science & Engineering
University of New South Wales
 Advanced Operating Systems 
 COMP9242 2002/S2 

Register message format

Registers (s0 ...s7 on MIPS R4k) contain:

• some (possibly zero) 2-word fpage descriptors,
• followed by data

fpage descriptors

by-value data

• presence of fpages is indicated by the -bit in snd_msg or rcv_msg.
• fpage processing stops if invalid fpage descriptor found
• remainder (or all) of register data is simply copied

Size is specified in l4/ipc.h:l4_ipc_reg_msg_t.

.