users February 2018

users@lists.genode.org

22 participants
26 discussions

Individual file access
by Nobody III 16 Mar '18

16 Mar '18

To start off, I'm planning on building a component that handles file open/save requests for other components, primarily graphical applications. My plan is to use a qt5 QFileDialog for the user to select one or more files, then modify the vfs server's configuration to attach the selected file(s) to the component's filesystem. To attach individual files to a component's filesystem, it seems like I should write a server-side link vfs plugin. The plugin would be like a symlink, but would transparently resolve the link within the vfs server, providing access to otherwise inaccessible files. Is this possible? If so, can you give me some tips on how to implement it?

2 7

Memory write tracing/logging of an application / Watchpoints in Genode/Fiasco.OC
by Stark, Josef 14 Mar '18

14 Mar '18

Hi all, I want to be able to 'trace' every memory write access of an arbitrary target application, in order to 'duplicate' those writes into another memory location. So that I would then have at all times one exact copy of the memory area (stack and heap) used by that application. My plan was to realize this with the help of a parent application, that acts as a session-proxy for the target, i.e. target requests a RAM-session from parent, which forwards the request to core and then provides the session to target; thus, the parent later knows which dataspaces/ memory areas are used by target. It could then flag that whole memory area with watchpoints. Hence, parent would be notified about all write accesses made by target and could consequently duplicate those writes in a secondary memory location. (I know that this would probably incur a slowdown factor of 10-1000 times, but that is allowed in this scenario.) Sadly, only now I have read that watchpoints are not implemented in Genode, and most probably neither are they in the underlying kernel, Fiasco.OC, which I have to use; breakpoints on the other hand seem to work just fine. My question is: Could there possibly be another way to achieve my goal, or do I have to bite the bullet and implement watchpoints myself? Thanks for bearing with me and for any hints at all. Best, Josef

4 16

Segmentation fault in free_io_mem
by Johannes Kliemann 13 Mar '18

13 Mar '18

Hi all, while testing the IO_MEM session on Linux with ACPI I noticed that the acpi_drv segfaults when freeing its io memory on repos/os/src/drivers/acpi/acpi.cc:1304 [1]. The crash happens then in repos/base/include/base/allocator.h:319 at > operator delete (obj, dealloc); I noticed that this is called many times without problems but not from free_io_mem. Unfortunately I have to admit that my C++ knowledge is insufficient to really grasp what happens in this expression. Is there any difference in how io memory is freed or should there be any (at least on Linux)? Regards, Johannes [1]: https://github.com/jklmnn/genode/blob/c2e9d35010a8a3c4f79d51d022cb3e5beb6f0… [2]: https://github.com/jklmnn/genode/blob/c2e9d35010a8a3c4f79d51d022cb3e5beb6f0…

2 2

Quota Preservation
by Nobody III 13 Mar '18

13 Mar '18

I sent this last year, but nobody responded, and I still need an answer. The RAM preservation feature in init is very nice; I used to have issues with init running out of memory. However, the RAM reservation applies after first reserving the RAM for all of the child processes based on their quotas. That may be fine in most cases, but it doesn't work properly when you give a child process a huge RAM quota to ensure that it gets all of the available RAM. In that situation, the RAM preservation happens after all of the available RAM has been reserved for the child processes, leaving no RAM available for init to preserve for itself. Something needs to change here. Changing the ordering is the simplest solution, but there may be a better solution. When we reserve all the remaining RAM for a particular process, we supply a huge RAM quota that is much larger than the process actually needs. It seems that the solution would be to split the quota numbers into a minimum (amount *reserved*) and a maximum (amount *available*). It would work very nicely for standard desktop workloads, especially when web browsers are involved. For example, I'd like to ensure that chromium has access to up to 2G of RAM, if it is available, but I don't want to reserve 2G of RAM specifically for chromium. Would this solution work well? Or is there something that I'm missing here?

2 6

32 bit overflow in timer
by Johannes Kliemann 06 Mar '18

06 Mar '18

Hi all, I noticed a 32 bit overflow in the Timer::Connection sleep functions and triggers. Calling usleep or trigger_once with an hour (3 600 000 000 us) works but calling it with two hours (7 200 000 000 us) causes something to overflow and stop the timer after 2 905 032 704 us which equals 7 200 000 000 & (2^32 - 1). As far as I have checked this these functions use the unsigned long which is indeed 64 bit but I think at some point only 32 bit are used. Is this intended behaviour? If so I think it would make sense to give out a warning at least. Regards, Johannes

4 7

Bender and GRUB1 "legacy"
by Valery V. Sedletski 05 Mar '18

05 Mar '18

Hi, I tried to boot Genode scenarios from my bootable flash stick. It uses GRUB 1 "Legacy".Â Tried to boot Genode/Nova with bender with GRUB "legacy" (actually, GRUB4DOS). I have the following entries in menu.lst: titleÂ Sculpt scenario (Genode/Nova) kernel /genode/bender module /genode/hypervisor hypervisor iommu serial novpid novga module /genode/sculpt/image.elf image.elf This scenario just hangs when booting. Does this work with GRUB2 only? In GRUB2, I see loading the "multiboot2.mod" module. Is this a new version of Multiboot protocol? Could Bender work with older version of multiboot protocol? Or, is it possible to use Genode/Nova without Bender somehow with GRUB1? Also, is it possible for Genode build system to avoid assembling all modules into image.elf, so I could load them separately as multiple modules? (at least, older Genode versions did so) 10nx in advance! WBR, valery

4 19

QProcess/QProcessEnvironment not declared
by Nobody III 01 Mar '18

01 Mar '18

I've been trying to port various Qt apps, including qt5ct, and I've run into errors such as "error: ‘QProcessEnvironment’ was not declared in this scope". I get that QProcess doesn't work on Genode, given its lack of fork() support outside noux, but why won't anything using QProcess or QProcessEnvironment compile, and how do I fix this?

2 1

Genode OS Framework version 18.02 released
by Norman Feske 28 Feb '18

28 Feb '18

Hereby, I proudly announce the release of Genode 18.02, which features the first revision of Sculpt OS, which is the Genode-based operating system that our team at Genode Labs has been using for several months now. For the release, we have taken the time to polish and document it so that like-minded people can join us with using and improving Genode day to day. Even though most topics of the release are closely related to Sculpt, many of them are interesting on their own account. The highlights are: - Sculpt for Early Adopters (EA) - On-target package installation and deployment - Improved networking stack - Support for servers written in the Nim language - VirtualBox version 5.1.32 - New trace-logging component - Ethernet-driver for i.MX-based Wandboard - SMP support for Xilinx Zynq hardware The complete release documentation is available at: https://genode.org/documentation/release-notes/18.02 I wish you a lot of fun with exploring the new release! Cheers Norman -- Dr.-Ing. Norman Feske Genode Labs https://www.genode-labs.com Â· https://genode.org Genode Labs GmbH Â· Amtsgericht Dresden Â· HRB 28424 Â· Sitz Dresden GeschÃ¤ftsfÃ¼hrer: Dr.-Ing. Norman Feske, Christian Helmuth

1 0

Config update timing
by Nobody III 27 Feb '18

27 Feb '18

What guarantees are there regarding config update timing? For example, if a process requires a policy change to get access to a required service, is the server guaranteed to get the config update before the service request? When we bring in a filesystem, e.g. ram_fs, how does that affect things? It seems that the chain of asynchronous notifications would destroy timing guarantees.

2 1

Fiasco.OC development version available on github
by Matthias Lange 21 Feb '18

21 Feb '18

Hi, Kernkonzept proudly announces the availability of a development version of the Fiasco.OC microkernel on github [1]. It features a detailed history and will be updated regularly. Those interested in exploring the latest changes can amend the latest L4Re snapshot release (see [2]) with this development version. We plan to release development versions of the build system and selected userspace components in the weeks ahead. So, let us know what you think. Cheers, Matthias. [1] https://github.com/kernkonzept/fiasco [2] https://l4re.org/download.html -- Matthias Lange, matthias.lange@...272..., +49-351-41 888 614 Kernkonzept GmbH. Sitz: Dresden. Amtsgericht Dresden, HRB 31129. GeschÃ¤ftsfÃ¼hrer: Dr.-Ing. Michael Hohmuth

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users February 2018