Abstract: A method and apparatus for performing a system call in a system having a user privilege level and a kernel privilege level, wherein the kernel privilege level is higher than the user privilege level is disclosed. A sequence of instructions is executed at the user privilege level including a first instruction that requires a resource provided at the kernel privilege level. Control is transferred to a first procedure executing at the user privilege level by performing a near call and saving only a pointer to the first instruction. The first procedure includes a calling instruction that does not save an architectural state prior to transferring control. Control is transferred from the first procedure to a second procedure executing at the kernel privilege level. The second procedure determines the resource required by the first instruction. Control is transferred from the second procedure to a third procedure that is determined by the second procedure.

Abstract: A method and apparatus for dynamically allocating system memory using a binary tree organized in an address and size dependent manner. Within the prior art, dynamic memory allocation methods were not portable to virtual memory addressing systems wherein local memory and system memory were joined in a continuous region of linear addresses. The allocation method of the present invention utilizes a binary tree of free memory block headers, corresponding to free memory blocks. Each free memory block header has an address field and a translation table field. The address field corresponds to a virtual address of the free memory block. The translation table field points to an entry within a translation table that is used to map the virtual address to a block in system memory.