Staged Allocation: Engineering the Specification and Implementation Of Procedure . . .

We present staged allocation, a new technique for specifying calling conventions. A specification written using staged allocation has a precise, formal semantics, and it can be executed directly inside a compiler. An implementation takes about 250 lines of ML or 650 lines of C++. Descriptions of nine calling conventions range in size from 15 to 30 lines each

Rethinking the Library OS from the Top Down

“There is nothing new under the sun, but there are a lot of old things we don’t know.” – Ambrose Bierce, The Devil’s Dictionary This paper revisits an old approach to operating system construction, the library OS, in a new context. The idea of the library OS is that the personality of the OS on which an application depends runs in the address space of the application. A small, fixed set of abstractions connects the library OS to the host OS kernel, offering the promise of better system security and more rapid independent evolution of OS components. We describe a working prototype of a Windows 7 library OS that runs the latest releases of major applications such as Microsoft Excel, PowerPoint, and Internet Explorer. We demonstrate that desktop sharing across independent, securely isolated, library OS instances can be achieved through the pragmatic reuse of networking protocols. Each instance has significantly lower overhead than a full VM bundled with an application: a typical application adds just 16MB of working set and 64MB of disk footprint. We contribute a new ABI below the library OS that enables application mobility. We also show that our library OS can address many of the current uses of hardware virtual machines at a fraction of the overheads. This paper describes the first working prototype of a full commercial OS redesigned as a library OS capable of running significant applications. Our experience shows that the longpromised benefits of the library OS approach—better protection of system integrity and rapid system evolution—are readily obtainable

Composing OS extensions safely and efficiently with Bascule

Library OS (LibOS) architectures implement the OS personality as a user-mode library, giving each application the flexibility to choose its LibOS. This approach is appealing for many reasons, not least the ability to extend or customise the LibOS. Recent work with Drawbridge [29] showed that an existing commodity OS (Windows 7) could be refactored to produce a LibOS while retaining application compatibility. This paper presents Bascule, an architecture for LibOS extensions based on Drawbridge. Rather than relying on the application developer to customise a LibOS, Bascule allows OS-independent extensions to be attached at runtime. Extensions interpose on a narrow binary interface of primitive OS abstractions, such as files and virtual memory. Thus, they are independent of both guest and host OS, and composable at runtime. Since an extension runs in the same process as an application and its LibOS, it is safe and efficient. Bascule demonstrates extension reuse across diverse guest LibOSes (Windows and Linux) and host OSes (Windows and Barrelfish). Current extensions include file system translation, checkpointing, and architecture adaptation. 1