91 results about "64-bit computing" patented technology

A processor has multiple operating modes, such as the long / compatibility mode, the long / 64-bit mode and the legacy modes of the x86-64 microprocessor. Different software entities execute in different ones of these operating modes. A switching routine is implemented to switch from one operating mode to another and to transfer control from one software entity to another. The software entities may be, for example, a host operating system and a virtual machine monitor. Thus, for example, a virtual computer system may comprise a 64-bit host operating system and a 32-bit virtual machine monitor, executing on an x86-64 microprocessor in long mode and legacy mode, respectively, with the virtual machine monitor supporting an x86 virtual machine. The switching routine may be implemented partially or completely in an identity-mapped memory page. Execution of the switching routine may be initiated by a driver that is installed in the host operating system of a virtual computer system.

A method and apparatus for managing shared virtual storage in an information handling system in which each of a plurality of processes managed by an operating system has a virtual address space comprising a range of virtual addresses that are mapped to a corresponding set of real addresses representing addresses in real storage. The virtual address spaces are 64-bit address spaces requiring up to five levels of dynamic address translation (DAT) tables to map their virtual addresses to real addresses. One or more shared ranges of virtual addresses are defined that are mapped for each of a plurality of virtual address spaces to a common set of real addresses. The operating system manages these shared ranges using a system-level DAT table that reference a shared set of DAT tables used by the sharing address spaces for address translation, but is not attached to the hardware address translation facilities or used for address translation. The shared range of virtual addresses straddles the 242-byte boundary between ranges served by different third-level DAT tables and is situated between a lower private range and an upper private range so that an individual address space can map both a lower private range and a shared range using only three levels of DAT tables. Each shared address range may be shared with either global access rights, in which each participating process has the same access rights, or local access rights in which each participant may have different access rights to the given range. Access rights for each participant may be changed over the lifetime of the process.

The dual mode bus bridge accommodates either two 64-bit personal computer interface (PCI) buses or four 32-bit PCI buses. In either case, only a single load is applied to the host bus. The dual mode bridge includes a bridge controller unit connected to a pair of expansion bridge units by respective internal buses. Each expansion bridge unit includes two sets of 64-bit wide queues and buffers. For 32-bit PCI operation, the two sets of queues and buffers are operated in parallel. For 64-bit PCI operation, the two sets of queues and buffers are linked together so as to appear in series to provide a single queue structure having twice the depth of the separate queue structures for a 32-bit mode operation. As such, undue duplication of queue and buffer resources is avoided. Method and apparatus embodiments of the invention are described.

Prior art attempts to provide 32-bit addressing within a 64-bit computing environment lead to other complications. Hardware solutions result in more complicated hardware which, in turn, increases costs and may reduce the functionality of 64-bit computing and significant changes to commercially available 64-bit processors. Alternatively, previous software solutions are computationally expensive, requiring add and subtract routines convert between 32-bit addresses and 64-bit addresses. An additional problem, specific to IBM™ zSeries hardware, is that the only way to provide a heap size larger than 2 GB, even if less than 4 GB, is to employ the 64-bit addressing in combination with a computationally expensive software patch to emulate 32-bit addressing. By contrast, provided by aspects of the present invention there are systems, methods and computer program products for implementing low-cost pointer compression and decompression. In accordance with more specific aspects of the invention, the systems, methods and computer program products for implementing low-cost point compression and decompression can be specifically adapted to compress 64-bit pointers to 32-bit pointers, and conversely convert 32-bit pointers to 64-bit pointers.

A memory system provides data error detection and correction and address error detection. A cyclical-redundancy-check (CRC) code generates address check bits. A 32-bit address is compressed to 6 address check bits using the CRC code. The 6 address check bits are concatenated with 64 data bits and 2 flag bits to generate a 72-bit check word. The 72-bit check word is input to an error-correction code (ECC) generator that generates 12 check bits that are stored in memory with the 64 data bits. A 76-bit memory module can store the 64 data and 12 check bits. Nibble errors can be corrected, and all nibble+1 bit errors can be detected. Also, a 6-bit error in a sequence of bits can be detected. This allows all errors in the 6-bit CRC of the address to be detected. The CRC code and ECC are ideal for detecting double-bit errors common with multiplexed-address DRAMs.

One embodiment of the present invention provides a system that uses an M-bit operating system (OS) kernel to support N-bit user processes. During operation, the system receives an exception. Note that the exception can be any event that needs to be handled by executing OS kernel code. Specifically, the exception can be a hardware interrupt, a software interrupt, an asynchronous interrupt, a synchronous interrupt, a signal, a trap, or a system call. Next, the system handles the exception by first switching the processor to the M-bit mode, and then executing M-bit OS kernel code which is designed to handle the exception. Note that the processor may primarily be designed to operate in the N-bit mode; the M-bit mode may primarily be provided for backward compatibility reasons.

The invention provides a DMA controller access implementation method for Loongson blade large-memory address devices. A management control module applies for a 256M address space in a memory; when a DMA controller and an address space lower than 32 bits carry out data transmission, data are transmitted according to the conventional DMA transmission mode; when the DMA controller and an address space higher than 32 bits carry out data transmission, the DMA controller sends an access address to an address-parsing module, the address-parsing module parses and then sends the address to an address conversion module, the address conversion module converts the address, and a mapping module carries out memory mapping according to the address converted by the address conversion module to map the address higher than 32 bits into the memory for which the management control module applies in advance. The method effectively solves the problem that a 32-bit Loongson CPU (central processing unit) cannot support memories exceeding the 32-bit address, and thereby the Loongson CPU can use a 64-bit address space at most.