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Changes between Version 47 and Version 48 of FAQ

2017-05-25T19:30:06Z (5 years ago)
Jakub Jermář

Add two paragraphs on comparison with L4Re


  • FAQ

    v47 v48  
    101101Compared to this, HelenOS is a coherent combination of a single portable microkernel and a multiplatform userland designed and built natively for it from fine-grained components. We strongly prefer designing and implementing our own components to importing foreign components from other systems and wrapping them into bloated compatibility layers, especially when dealing with the critical core components of the operating system. HelenOS supports basic resource accounting, but currently not so elaborate as in the case of Genode. Unlike Genode components, HelenOS components are not organized in a strict hierarchy and the whole system structure is rather flat.
     103=== How is HelenOS different from L4Re? ===
     105[ L4Re] is a multiserver operating system built on top of the Fiasco.OC microkernel. As of release !r72, it runs on amd64, arm32, ia32, mips32 and mips64 processor architectures, supports SMP and specializes in virtualization. Above the microkernel runs a set of userspace components that fall into several categories: native L4Re components (such as the root and init tasks, I/O manager, drivers and virtual machine monitors), or paravirtualized VMs (`L4Linux`), or fully-virtualized VMs, or third-party components serving demonstration purposes. The runtime scenarios are mostly statically setup by the init task and the I/O manager according to a pair of Lua scripts.  L4Re provides a POSIX interface which allows it to use quite a few contributed packages. L4Re also uses a mixture of native and third party device driver and server components. Notably, the latter has been enabled by the DDE framework which imports portions of Linux 2.6.29, allowing the reuse of compatible Linux device drivers. Alternatively, L4Re can use `L4Linux` as a driver OS. The released version contains traces of a networking server that combines Linux NIC drivers, DDE and the lwIP networking stack. This component has been however disabled and marked broken as of release !r72.
     107In comparison, HelenOS supports a slightly different set of processor architectures and despite some experimental master theses' results does not currently engage in virtualization. Instead it aims to provide a coherent, dynamic, single-user system composed of many fine-grained components. HelenOS almost exclusively rolls its own original drivers, frameworks, GUIs, networking and filesystems.
    103109== Advocacy-related Questions ==