T-Kernel Specification (1.B0.02)

4.10. SUBSYSTEM MANAGEMENT FUNCTIONS 215
shown in Figure 4.15, resource control blocks with resource IDs #1, #2, and #3 must automatically be
created for the subsystem.
[Additional Notes]
A resource ID is in some cases used also as a logical space ID (lsid). Resource IDs should therefore be
assigned values that can be used directly as logical space IDs or that can easily be converted for use as
logical space IDs.
A system resource group always exists as a special resource group. One system resource group always
exists, moreover, from the time the system boots, without waiting for creation by tk cre res. The
system resource group cannot be deleted. Other than the requirement that it must always exist, a
system resource group is no different from other resource groups.
Resource control block creation might be implemented in either of the following ways.
(A) At the time of subsystem definition (tk def ssy), create as many resource control blocks as the
maximum number of resource groups, and use tk cre res simply to assign them.
(B) Use tk cre res to create as many resource control blocks as there are subsystems and assign
them.
Since the specification requires clearing a resource control block to 0 when it is initially created, the
timing of this clearing to 0 differs between methods (A) and (B). This difference should not have much of
an effect; but since method (A) will have fewer cases of clearing to 0, subsystems must be implemented
assuming (A). Method (A) is also recommended for the OS implementation.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02