From gesimu at gmail.com Sun Aug 11 22:05:03 2019 From: gesimu at gmail.com (Simon Gerber) Date: Sun, 11 Aug 2019 22:05:03 +0200 Subject: [Barrelfish-users] exokernel In-Reply-To: References: Message-ID: Hi Arnkjell, Not sure if someone else already replied directly to you, but I'll give my two cents anyway :) Barrelfish already utilizes Exokernel principles in the sense that user applications by default link against libbarrelfish. libbarrelfish acts as a library OS which provides higher-level convenience abstractions around the raw Barrelfish syscall interface which is built around seL4-like capabilities and not particularly user-friendly. Note however, that applications are not required to link against libbarrelfish. However, most applications do, as libbarrelfish abstracts away quite a lot of boilerplate which the Barrelfish architecture brings, such as tedious capability-based memory management, message channel setup, message and event handling, etc. Note that even applications which link against libbarrelfish can still interact with the lower-level interfaces to implement features which are not provided out of the box by libbarrelfish, e.g. copy-on-write memory regions. One area where Barrelfish could be improved from an engineering perspective is the modularity of the library OS could be vastly improved, and libbarrelfish could be split in multiple more or less loosely coupled libraries which applications can individually link against. However, the coupling of libbarrelfish is quite tight in places, and some parts are quite interlinked out of necessity, e.g. memory management and cspace management. So, to answer your question in short, while the multikernel design doesn't say anything about exokernel or not, its implementation in Barrelfish is already a "exo-multikernel" if you wish, as the CPU drivers themselves were kept rather small right from the beginning. Hope this helps, -- Simon -- github.com/simu On Tue, 2 Jul 2019 at 00:06, Arnkjell Eriksen wrote: > > Would an exo-multikernel make sense or be feasible? > > > _______________________________________________ > Barrelfish-users mailing list > Barrelfish-users at lists.inf.ethz.ch > https://lists.inf.ethz.ch/mailman/listinfo/barrelfish-users