| 摘要 |
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 2<42>-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.
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