diff --git a/doc/release_notes-19-02.txt b/doc/release_notes-19-02.txt new file mode 100644 index 0000000000..5366970f73 --- /dev/null +++ b/doc/release_notes-19-02.txt @@ -0,0 +1,836 @@ + + + =============================================== + Release notes for the Genode OS Framework 19.02 + =============================================== + + Genode Labs + + + +In our [https://genode.org/about/road-map - road map] for 2019, we stated +our goal to make Genode more relevant and appealing for a broader community. +The current release takes a big leap towards that goal: It opens up Sculpt +OS for 3rd-party software providers, introduces a federated blogging +platform about Genode-related topics, and makes the world's +[https://www.tiobe.com/tiobe-index/ - most popular] programming language +(Java) available to Genode users. + +With the 4th stage of the evolution of Sculpt OS - themed as "community +experience" (CE) - Genode's custom general-purpose OS introduces a novel and +simple way for users to discover software, and for software providers to +announce software. There is no middle man like an app store or a distribution! +We hope that this federated model of software provisioning and deployment will +have a vitalizing effect on the community around Genode. On a practical level, +the interactivity of the new version is a playful and fun experience. Section +[Sculpt OS as a community experience (CE)] gives a rough overview about +*Sculpt CE*. A ready-to-use disk image will be released mid of March. + +When speaking of "software providers", we don't think of anonymous +repositories. Software - and Free Software in particular - is developed and +provided by individuals after all. So in our federated way of software +distribution, we want to highlight this individuality. For this reason, we +launched a new blogging platform for Genode-related stories called +[https://genodians.org - Genodians.org], which gives everyone who is +enthusiastic about Genode - users and developers alike - a platform to express +ideas, announce software, or share practical tips and tricks. As explained in +the [https://genodians.org/nfeske/2019-01-07-welcome - initial posting], +*Genodians.org* is - in the spirit of Sculpt's software distribution model - +also organized in a federated way. The content is hosted and remains +completely under control by the respective authors. The website merely +aggregates and presents the content. It goes without saying that Genodians.org +is based on Genode. The system image that contains the entire web appliance - +from the kernel over the content management to the web server - is contained +in a 8 MiB disk image. +Section [Genodians.org as a showcase of a Genode-based web appliance] goes +into more detail. + +We identified the support of popular programming languages as one key aspect +to attract a broader community. With the current release, our port of +*OpenJDK* (Section [Java]) for both 64-bit x86 and 32-bit ARM has reached a +mature state suitable for the creation of web services. This paves the way +towards quite exciting new system creations, like the *Boot2Java* system +presented in Section [Showcase of a Java-based network appliance]. +On the account of programming-language support, we are happy to announce +a vastly improved runtime support for *Ada* and *SPARK* (Section +[Ada and SPARK] as well as the initial support for OCaml (Section [OCaml]). + +Besides the work on shiny features, the current release cycle included a +profound *spring cleanup* described in Section +[Base framework and OS-level infrastructure]. +It thereby finalizes the huge API modernization initiated almost three years +ago. + + +Sculpt OS as a community experience (CE) +######################################## + +When we laid out the road map for Sculpt OS a little more than one year ago, +we envisioned four stages of development. Sculpt EA was geared towards +die-hard early adopters facilitating the live editing of the system using a +text editor. Sculpt TC was targeted at "the curious" and included a graphical +user interface for common administrative tasks. Sculpt VC introduced the +visual composition of the system using an interactive graph. Even though +Sculpt already allowed for the installation of components from different +software providers at this stage, it offered no simple means to discover +software and the installation still required the manual editing of "launcher" +text files. + +The final - community experience - stage of the plan ought to foster the +federated provisioning of software. Software providers should have the ability +to announce new packages. Conversely, users should be able to "subscribe" to +such announcements, similar how one would subscribe to an RSS feed. Once +software is discovered in this way, it should take only a few clicks to +install and integrate it into the running Sculpt system. No command-line +interface should stand in the way of discovery. + +Sculpt CE is the realization of this idea. + +For Sculpt users, the discovery starts at the '+' menu. In contrast to Sculpt +VC where the menu offered a rather long list of components to choose from, the +menu now offers nothing to be excited about. + +[image sculpt_ce_menu] + +However, at the very bottom, there is a new menu entry "Depot ...", which +leads to a sub menu with a list of enabled software providers. If connected to +the network, it also shows an entry named "Selection ...". + +[image sculpt_ce_menu_depot] + +The "Selection" sub menu allows the user to enable software providers. + +[image sculpt_ce_selection] + +When clicking on one of the checkboxes, the package index of the provider is +downloaded and the checkbox is highlighted. In the example, "nfeske" is +already enabled. + +By clicking on the top-left triangle, one can always go one menu up. Back in +the depot menu, selecting a software provider will now display the index of +available packages. When selecting a new package, it can be installed via a +single click: + +[image sculpt_ce_install] + +Once the package is installed, the menu takes the user to a dialog for +integrating the package as a new component into the running Sculpt system. For +each resource required by the package, the user can decide how to connect it. +For example, the file system to be mounted at _/config/_ of a fresh +noux-system instance can be routed to any file system service the user wishes. +The noux-system won't know which file system is selected. It will just work +with it. + +[image sculpt_ce_routes] + +As soon as all routes are defined, the dialog presents a button for adding the +component to the system. + +Using this interactive work flow, the discovery of software and its +integration becomes a rather playful process. + +To make a once composed system permanent, one can use the inspect window to +copy the _/config/managed/deploy_ file to the _config/19.02/ directory of your +Genode partition. This way, the deployment configuration will take effect +immediately at boot time. + +Genode 19.02 comes with Sculpt CE included. As usual, we will take a bit +of time following the release for thorough testing and refining before +announcing an updated disk image mid March. We would greatly appreciate +your feedback during this phase! For baking a fresh Sculpt image, please +refer to the +[https://genode.org/documentation/articles/sculpt-vc - documentation] +of Sculpt VC, but using the Git tag '19.02' instead of 'sculpt_vc'. + + +Announcing software packages +---------------------------- + +The community experience of Sculpt CE will ultimately depend on the +participation of software providers. To become listed in the selection dialog +mentioned above, you may consider including your public key and download +location at the Genode repository +[https://github.com/genodelabs/genode/tree/master/depot - at /depot/]. + +For the announcement of packages, a software provider can publish so-called +"index" files for a particular Sculpt version in the software provider's +depot. E.g., the index of packages supported on Sculpt 19.02 would be located +at _index/19.02_ within the depot. Like any other depot content, index files +are digitally signed. An example index for the software provider "nfeske" +would look as follows: + +! +! +! +! +! +! +! + +Each '' node refers to a package with a concrete version and a short +description. By nesting '' nodes, software categories can be defined. + +Index files can be published like any other depot content using the +_depot/publish_ tool, which takes care about compressing and digitally signing +the published information: + +| ./tool/depot/publish nfeske/index/19.02 + +To ease the updating of the index with current package versions, the +_sculpt.run_ script creates the _depot/index/_ file from the input +found in _repos/gems/run/sculpt/index_. The latter file is void of any version +numbers. + +For any questions about the process, please consult the Genode +[https://genode.org/community/mailing-lists - mailing list]. + + +Showcase of a Java-based network appliance +########################################## + +With OpenJDK in good shape (Section [Java]), we have created a Genode scenario +that demonstrates JVM's ability to execute well on embedded hardware. As +target platform, we choose an ARM (i.MX 6) based SoC with two integrated +network interface controllers. In the scenario, the Genode system boots +directly into a Java application, which in turn spawns two HTTP server +instances where each instance communicates through a dedicated NIC. Both +server instances run as one Java program. + +[image java_nic_filter] + +The Java application (a JAR file) is loaded from the board's SD card, and +therefore, can easily be replaced. If you are interested in Java and ARM SoC, +the full details and a step by step instruction can be found at our +[https://genodians.org/ssumpf/2019-02-27-java-19-02 - Genodians.org] site. + + +Genodians.org as a showcase of a Genode-based web appliance +########################################################### + +[https://genodians.org - Genodians.org] is our take on a federated blogging +platform about Genode-related topics. It does not host the actual content +but rather aggregates content hosted elsewhere. + +[image genodians] + +The site periodically fetches content in the form of zip archives containing +raw text and PNG images, extracts the archives, and transforms the text into +HTML using a custom static site generator. The result of the transformation +process is served by the lighttpd web server. + +This system is based on Genode and can be found here: + +:Genodians.org repository: + + [https://github.com/genodelabs/genodians.org] + +A few noteworthy technical points about the site: + +* The periodic process of downloading, extracting, and transforming content + is realized via the 'fetchurl', 'extract', and 'sequence' components. + +* The textual content uses the markup of the + [https://github.com/nfeske/gosh - GOSH] + text processing tool, which is similar to + [https://daringfireball.net/projects/markdown/ - Markdown]. + +* The custom static site generator consists of a plain makefile and a few GOSH + style files. The makefile is executed within a noux instance, which is + Genode's custom Unix runtime environment. It is re-spawned for each + iteration. As GOSH is written in Tcl, the tclsh is used within the noux + environment. + +* The lighttpd web server uses a statically supplied SSL certificate. + +* The most time-consuming part of creating Genodians.org was the CSS + definition. + +* The entire system image is about *8 MiB* in size. It includes the following + ingredients: + * Kernel (e.g., NOVA), + * Basic Genode components such as init, NIC router, the VFS server, + * Network driver (based on iPXE), + * Linux TCP/IP stack as a library, + * Curl, libssh, libssl, libcrypto, lighttpd + (for downloading and serving content), + * libarchive, zlib, liblzma (for extracting the downloaded content) + * Noux, coreutils (stripped down), bash, GNU make, and tclsh (for + transforming text into HTML) + +More information about the site's inner working will be posted in a series +of articles - guess where? - at Genodians.org! + + +Base framework and OS-level infrastructure +########################################## + +Removal of deprecated APIs +========================== + +Almost three years ago - +with [https://genode.org/documentation/release-notes/16.05 - version 16.05] - +we started the transition to Genode's modern API. One year later - in +[https://genode.org/documentation/release-notes/17.05#Completed_component_transition_to_the_modern_API - version 17.05], +we announced the completion of this transition but we retained the deprecated +APIs to accommodate Genode users that picked up the new API only gradually. +With the current release, we finally drop the deprecated APIs along with a +couple of other legacies: + +* The _base/timed_semaphore.h_ has been removed. In hindsight, officially + providing this utility was a big mistake because it lured developers into + a wrong direction. In fact, we found that there is no legitimate use of it + when a component is designed in a clean way. If a component relies on a + timed semaphore, it should better be redesigned. There are two noteworthy + places where a timed semaphore is still used as a band-aid solution: + the 'pthread_cond_wait' implementation of the libc, and DDE for rump + kernels. Those places now host a private copy of the timed semaphore, but + should ultimately be reworked. + +* The header _base/printf.h_ has been removed along with the log back end + for 'printf'. The 'Console' with the format-string parser is still there + along with 'snprintf.h' because the latter is still used at a few places, + most prominently the 'Connection' classes. + +* The notion of a 'Ram_session' exists no more since the former RAM-session + interface was merged into the PD-session interface in + [https://genode.org/documentation/release-notes/16.05#Consolidation_of_core_s_SIGNAL__CAP__RM__and_PD_services - version 16.05]. + Still, the types were preserved (by typedefs to 'Pd_session') to keep up + API compatibility. Those last traces of 'Ram_session' are gone now. The + 'Env::ram()' accessor returns the 'Ram_allocator' interface, which is a + subset of the 'Pd_session' interface. + +* The use of the global 'Genode::env()' accessor function is not possible + anymore. + +* The old 'Child_policy::resolve_session_request' interface that returned + a 'Service' instead of a 'Route' has been removed. + +* Boolean accessor methods are no longer prefixed with 'is_'. E.g., instead + of 'is_valid()', use 'valid()'. + +* All connection constructors need the 'Env' as argument. + +* The 'Reporter' constructor needs an 'Env' argument now because the + reporter creates a report connection. + +* The old notion of 'Signal_dispatcher' is gone. For receiving + asynchronous notifications, the 'Signal_handler' interface must be used. + +* Transitional headers like _os/server.h_, _cap_session/_, + _volatile_object.h_, _os/attached*_dataspace.h_, and + _signal_rpc_dispatcher.h_ have been removed. + +* The distinction between 'Thread_state' and 'Thread_state_base' does + not exist anymore. Only 'Thread_state' prevails. + +* The header _cpu_thread/capability.h_ along with the type definition of + 'Cpu_thread_capability' has been removed. Use the type + 'Thread_capability' defined in cpu_session/cpu_session.h instead. + +* The _os/ram_session_guard.h_ has been removed. + Use 'Constrained_ram_allocator' provided by _base/ram_allocator.h_ instead. + + +Source-tree reorganization +========================== + +Timer moved from os to base repository +-------------------------------------- + +Traditionally, the user-level timer was hosted at the os repository at +_drivers/timer/_. However, since the timer and timeout handling have become +part of the base library (the dynamic linker), the component naturally belongs +to the base repository. It is now located at _base/src/timer/_ and +_base-/src/timer/_ respectively. + +Note that this change affects include paths for the former +_include/os/timer/_, _include/os/alarm.h_, and _include/os/duration.h_ +headers. Those can now be found in _include/base/_. + + +Consistent naming of block components +------------------------------------- + +Regarding the naming of files and APIs, Genode follows the convention of +avoiding abbreviations. Most components follow this convention, with the block +servers being the exception to the rule. Those were named "part_blk" or +"rom_blk". With the current release, we removed this inconsistency by renaming +those offenders, changing "blk" to "block". Closely related, abbreviations +like "cli" and "srv" have been replaced by "client" and "server". + + +Improved API safety +=================== + +XML-parsing API +--------------- + +Genode consistently uses XML for component configurations and for reports +generated by components. The latter are often consumed by other components. +This puts the XML parser into a prominent position. Genode's XML parser +comes in the form of the 'Xml_node' class. Since it was introduced before the +age of modern C++, it offers several risky "C-ish" methods, in particular +accessors that return pointers, raising memory-safety concerns. To promote a +safe programming style, the following parts of the interface are subject to +change now: + +* The 'Xml_node::addr', 'Xml_node::content_addr', and 'Xml_node::content_base' + accessors will be removed because it is all too easy to store the returned + pointers and forget about the lifetime of the originating 'Xml_node' object. + + Fortunately, in practice, those methods are rarely used because information + is typically represented in attributes, not as node content. However, to + still support the access to the raw content, the new + 'Xml_node::with_raw_node', 'Xml_node::with_raw_content', and + 'Xml_attribute::with_raw_value' methods call a functor taking the raw byte + buffer and size as arguments. This way, the lifetime of the pointer is + naturally bound to the scope of the functor. + +* The new 'with_sub_node' method calls a functor with the specified + sub node as argument and thereby reduces the need for the traditional + 'Xml_node::sub_node' method, which returns an 'Xml_node'. + The latter is risky because an 'Xml_node' contains a pointer to the actual + data. In contrast, the lifetime of the 'Xml_node' processed via the new + 'Xml_node::with_sub_node' is naturally bound to the scope of the passed + functor. + +* The 'Xml_attribute::value' and 'Xml_node::value' methods now take an + argument of type 'T &out' instead of 'T *out', which eliminates the + uncertainty of a possible nullptr argument. + +The original interface will still be available for a while but it will +eventually be removed. + + +Simplified session-policy handling +---------------------------------- + +Most server components make use of the 'Session_policy' utility for selecting +a client policy depending on the session label. However, the pattern of its +use remained a bit inconsistent across components, in particular the handling +of the case where no policy could be found. Some components outright +denied the session where others implemented a fallback to a built-in default +policy. This inconsistency is now removed. + +Following the principle of deny-by-default the absence of a matching policy +denies the session request. Since the 'Session_policy::No_policy_defined' +exception is a typedef to the 'Genode::Service_denied' exception, a server +does not need to explicitly handle it, which simplifies the implementation. +With this change, the 'No_policy_defined' case is always an error case. Hence, +the new version of 'Session_policy' prints a error message, which relieves the +server developer from implementing diagnostics in the server code. + +As a consequence of this change, scenarios that used to rely on the +policy-fallback approach of some servers - notably the NIC bridge, window +manager, the window decorators - need a slight adaption: To enable the +fallback to a default policy, a '' node must be explicitly +specified in the server's configuration. + + +Removed pointers from Genode::Fifo interface +-------------------------------------------- + +To make the use of the 'Genode::Fifo' data structure more safe, all methods +that return pointers have been replaced by methods that call a functor with +a reference as argument. + + +New server-side block-request stream API +---------------------------------------- + +The current block-component API (_os/include/block/_) was designed at a time +long before Genode's modern component API was introduced. Back then, the use +of blocking calls was prevalent. Today, we design components to work +asynchronously. The original block-server API was successively enhanced to +allow the implementation of asynchronous block servers but it remained "upside +down" while growing more complicated than it should be. + +To simplify the implementation and verification of block servers, the current +release introduces a modern API that will eventually replace the original +block-component API. The new API is called *block-request stream* and can be +found at +[https://github.com/genodelabs/genode/blob/master/repos/os/include/block/request_stream.h - os/include/block/request_stream.h]. +It is designed with the following considerations: + +* It anticipates the asynchronous operation of block servers by default. + Using the new API, such servers - in particular block-device drivers - can + be implemented as state machines triggered by client requests and device + interrupts. + +* It reinforces the memory safety of the server code by not returning any + pointers or references. + +* It relieves the server developers from handling special cases (like a + congested acknowledgement queue) while being flexible enough to accommodate + different categories of components like drivers, resource multiplexers + (part_block), and bump-in-the-wire components in a natural way. + +* It naturally supports the batching of requests as well as zero-copy + (device DMA directly into the client's communication buffer). + +The use of the new API is illustrated by the artificial test at +[https://github.com/genodelabs/genode/blob/master/repos/os/src/test/block_request_stream/main.cc - os/src/test/block_request_stream/]. +We plan to successively migrate all existing block servers to this new API +and will remove the traditional block-component API eventually. + + +GUI stack +========= + +Motivated by our work on Sculpt as described in Section +[Sculpt OS as a community experience (CE)], Genode's GUI stack received +the following improvements: + + +Window management +~~~~~~~~~~~~~~~~~ + +To improve the visual appearance of Sculpt's administrative GUI, the *themed* +*decorator* was enhanced with an option to disable decorations based on the +window label. By setting the 'decoration' attribute of a '' node to +"no", matching windows appear without any border, which is desirable for +Sculpt's component graph. + +Furthermore, the themed decorator accepts the '' attribute +'motion='. The default value is 0. If a value higher than 0 is +specified, window-geometry changes are applied as an animation where the + denotes the number of animation steps. This feature is used for +smoothing the placement of Sculpt's component graph. + +The *motif* *decorator* - which is a nice alternative to the themed decorator - +is now giving visual feedback to mouse clicks. For example, while the user +drags a window by clicking on the window title, the title bar appears as +pressed, which creates an improved sense of responsiveness. + + +Unified shape-report routing +---------------------------- + +Applications propagate custom mouse-cursor shapes by issuing "shape" reports +towards the pointer component. The pointer component correlates the session +labels of the incoming shape reports with the label of nitpicker's currently +hovered client. Hence, an application's shape report session should take the +same route as its nitpicker session. + +The presence of the window manager as an intermediary of the nitpicker session +breaks this rule. Consequently, rather awkward label-rewriting magic was +required when routing shape reports originating from windowed applications. To +make the shape reporting more natural, the window manager has become able to +proxy shape reports on behalf of its clients. When routing a shape through the +window manager, the labels of both the nitpicker sessions as well as the shape +report sessions contain the intermediary "wm ->" part. + + +Unicode support for the graphical terminal +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The terminal has been changed to represent characters as 16-bit codepoints +internally. It thereby became able to display a much larger variety of +international characters when using a suitable font. Unicodes are sent through +the terminal session via bursts of UTF-8 bytes now. + +As a collateral change, the generic 'Codepoint' class became printable via +Genode's 'Output' interface. This way, a codepoint can easily be serialized +into UTF-8 bytes. + + +Programming languages +##################### + +Ada and SPARK +============= + +_The work described within this section was contributed by_ +_[https://componolit.com - Componolit]. Thanks to Alexander Senier_ +_and Johannes Kliemann for the fantastic collaboration!_ + +The integration of SPARK/Ada programs was improved greatly and the Ada runtime +was renamed to 'spark'. This emphasizes its main purpose: trusted components +that can be formally verified. A more feature-rich runtime based on 'libc' was +added to genode-world under the name 'ada'. + +Build system integration +------------------------ + +Up until now, the (deprecated) 'gnatmake' tool was used to build Ada object +files. This was unfavorable for two reasons: First, multiple invocations of +gnatmake would sporadically corrupt the compiler-generated Ada linker files +('.ali') and break parallel builds. Second, Ada dependency information did not +get propagated into Genode's build system such that certain source changes +failed to trigger a rebuild. + +For these reasons the 'gnatmake' tool has been dropped in favor of regular +compiler calls as done for all other languages. To facilitate consistent +rebuilds on source-code changes, the +[https://github.com/Componolit/ali2dep - ali2dep] tool was created. From an +'.ali' file, it produces '.d' files suitable for direct inclusion into +Genode's build system. + +Until the integration into the toolchain, 'ali2dep' support needs to be +enabled through the 'CUSTOM_ALI2DEP' variable (absolute path or command name +if the command is in 'PATH'). By default, a warning about the absence of the +tool is emitted and dependency information is not generated. You can add this +variable to the 'etc/tools.conf' of your build directory as follows: + +! CUSTOM_ALI2DEP = /path/to/ali2dep + +Elaboration code +---------------- + +Previously, Ada programs that required elaboration code to be run were +unsupported on Genode. With this release, Ada programs are bound using +'gnatbind', which results in elaboration code being generated. An additional +benefit comes in the form of proper error messages at compile time if, for +example, source code is missing or outdated. + +To run an Ada main program with elaboration, calls to 'adainit()' and +'adafinal()', generated by the binder, need to be added to your +component-construction code: + +! extern "C" void _ada_main(void); +! extern "C" void adainit(); +! extern "C" void adafinal(); +! +! void Component::construct(Genode::Env &env) +! { +! adainit(); +! _ada_main(); +! adafinal(); +! env.parent().exit(0); +! } + +Note, that the name of the Ada main program ('_ada_main()') in this example +depends on the name of your main procedure. + +Debug output +------------ + +Support for 'GNAT.IO' was added to the runtime. 'GNAT.IO' is a stripped-down +text I/O facility, which we map to a terminal session on Genode. Only output +is supported at the moment. A pointer to a terminal session has to be provided +to the ADA runtime in order to use 'GNAT.IO'. Please refer to +_repos/libports/src/test/gnatio/_ as an example. + +Unit testing +------------ + +To facilitate test-driven development of Ada components, the +[https://www.adacore.com/documentation/aunit-cookbook - AUnit] unit testing +framework was ported to Genode. It is located in the genode-world repository +whereas a usage example can be found at 'src/test/aunit'. Note that the full +Ada runtime ('ada') is required as the framework uses features not present in +the SPARK runtime. + + +Java +==== + +Since Genode release +[https://genode.org/documentation/release-notes/18.11#Java_language_runtime - 18.11], +we continued our effort to enable the just-in-time (JIT) compiler for OpenJDK. +We are happy to announce that we were able to achieve this goal. The JIT +compiler is now enabled as default for both x86 (64 bit) and ARM (32 bit), +which significantly improves the performance of the Java virtual machine for +these architectures. + +Additionally, we even further improved JVM's performance by taking advantage +of more aggressive compiler optimizations. This triggered some unidentified +bugs and led to a greatly enhanced stability of OpenJDK. + +For a small hello world example we offer a simple run script: + +! make run/java + +For a more complex scenario please refer to Section +[Showcase of a Java-based network appliance]. + + +Nim +=== + +Support for Nim has been removed from the Genode build system to encourage +building Nim components out-of-tree using the Nimble package manager. +The compatibility of the base system with the Nim runtime will be monitored +and improved regardless of this change. + + +OCaml +===== + +A proof-of-concept port of the OCaml bytecode interpreter has been placed +in the world repository. This allows simple programs that are compiled to the +bytecode instructions to be executed and is a first step in supporting the +OCaml language. This interpreter does not yet include the standard library. +Therefore only language primitives are available. Porting the standard library +appears to simply be a matter of defining a build process. The greatest +hurdle to porting existing OCaml applications would seem to be finding a path +into the workflow of the OPAM package tooling. + + +Libraries and applications +########################## + +New utility for taking screenshots +================================== + +The flif_caputure screenshot utility has been added to the world repository. +This utility implements a framebuffer and input service which it proxies to +its parent. When the utility observes the *PrtSc* key, it captures the content +of the framebuffer and writes it to the file system in the FLIF image format, +FLIF being chosen primarily for its uncomplicated API. To use the utility in +practice, the common case would be to run it as a client of the default window +manager with a second window manager stack running as a client of the capture +utility. This allows capture behavior and scope to remain simple and explicit. + +The background story behind the tool is covered by a dedicated +[https://genodians.org/ehmry/2019-01-31-flif_capture - posting] at Genodians.org. + + +Growing use of the Genode-World repository +========================================== + +The [https://github.com/genodelabs/genode-world - Genode-World] repository +contains software that is not strictly part of the official Genode OS +framework but rather supplemental. In particular, it contains ports of +3rd-party software to Genode. The pool of ported software is steadily growing, +which moves the world repository more and more into the spotlight of Genode +users. For example, among a variety of games and experimental components, our +port of [Java - OpenJDK] is also hosted there. To acknowledge the growing +importance of the world repository, we added the building of all world depot +archives to our nightly build tests. + +With this baseline of quality assurance in place, it was a good time to move +supplemental software such as Dosbox, FUSE, libav, libSDL, and its companion +libraries from the Genode repository to the Genode-World repository. Speaking +of libSDL, as part of the curation of the world content, the library back end +of libSDL has been changed to the direct use of the nitpicker session +interface instead of the lower-level framebuffer and input interfaces. Thanks +to this change, many scenarios could be greatly simplified, in particular +packages designated for the use in Sculpt OS. + + +Updated or removed 3rd-party software +===================================== + +The following 3rd-party software received an update: + +* OpenSSL updated to version 1.0.2q with 'SSL_CONF_*' enabled, + as needed by lighttpd's mod_openssl. + +* Lighttpd updated to version 1.4.52, with TLS enabled. + +* libpng updated to version 1.6.36 + +* jbig2dec updated to version 0.15 + + +Removal of VirtualBox 4 +----------------------- + +All regular users of Genode's VirtualBox port migrated to version 5 a long +time ago. Version 4 was still maintained because this is the only version +supported on the Muen separation kernel. However, since the focus of the Muen +developers recently moved towards the use of nested virtualization, our +version of VirtualBox 4 is no longer vital for Muen. So we could remove it. + + +Platforms +######### + +Board support for i.MX6 Quad Sabrelite and Nitrogen6 SoloX +========================================================== + +In 2018, we extended our device-driver support for NXP i.MX 5 and 6 based ARM +platforms. This year, we continue our commitment to this platform with +additional support for the NXP reference board i.MX6 Quad Sabrelite and the +Nitrogen6 SoloX, which features dual Gigabit Ethernet. + + +Resizeable virtual framebuffer on Linux +======================================= + +When executing Genode on Linux, we use a libSDL-based pseudo driver for +running graphical scenarios. This *fb_sdl* server has now been enhanced with +the ability to resize the SDL window. Such a resize event is translated into +Genode's framebuffer resize protocol. Thereby, the resizing of the host window +looks like a mode change to Genode's GUI stack. This greatly eases the testing +of the mode-change handling of components like the nitpicker GUI server. + + +Tooling and build system +######################## + +Enforced 'override' annotations +------------------------------- + +The '-Wsuggest-override' warning complains about implementations of virtual +functions that lack the override keyword. If the implementation of a virtual +method is marked as 'override' the compiler checks for a matching virtual +method in the base class. If there is no such method, the implementation +unexpectedly diverged from the interface. + +An interface may change over time, which is especially troublesome when it +contains a default implementation of a virtual method. Without 'override' +annotations, the compiler will silently add the outdated implementation of the +derived class as an overload of the interface's default implementation, which +introduces a subtle but potentially serious bug. + +To rule out such bugs in the future, we made 'override' annotations mandatory +when using the default strict warning level. + + +Generalized use of the depot by run scripts +------------------------------------------- + +With more and more run scripts using archives out of Genode's depot, we gained +experience with typical usage patterns. In particular, we found the universal +use of the configurable depot user preferable over the hard-wiring of +'genodelabs'. Hence the 'depot_user' function has become a built-in function +of the run tool. + + +Repeat mode for the depot-autopilot test environment +---------------------------------------------------- + +The _depot_autopilot.run_ script now supports the environment variable +'TEST_REPEAT' with the possible values 'until_forever' and 'until_failed'. +When specified, the tests are run in a loop. The latter argument is +particularly useful for reproducing sporadic errors. + + +New run script to execute a single test w/o the depot +----------------------------------------------------- + +The new _os/run/test.run_ script allows for the quick execution of an +individual test from the build directory while side-stepping the depot. +It expects a 'PKG' variable specifying the test package. E.g., + +! make run/test KERNEL=nova PKG=test-xml_node + +Note that it does not cover all test packages right now. +The tool and its limitations are explained in more detail by a dedicated +[https://genodians.org/nfeske/2019-02-05-shortcut-for-testing - posting] +at Genodians.org. + + +Support for undefined-behavior sanitizer +---------------------------------------- + +The +[https://developers.redhat.com/blog/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ - UndefinedBehaviorSanitizer] +(UBSan), also described in the +[https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html - GCC documentation], +can detect undefined behavior while a program is running. + +With the current release, this diagnostic feature of GCC becomes available for +analyzing Genode components. By specifying 'SANITIZE_UNDEFINED = yes' in a +'target.mk' file, the '-fsanitize=undefined' compiler flag is enabled and the +program is linked with libubsan and libsanitizer_common. The program has to +call 'env.exec_static_constructors()' and 'sanitizer_init(env)' upon startup +to initialize the sanitizer libraries. Whenever undefined behavior is detected +while the program is running, a "runtime error:" message including the source +code location of the error is printed to the log. +