users March 2018

users@lists.genode.org

27 participants
31 discussions

Library Isolation
by Nobody III 16 Mar '18

16 Mar '18

In Genode, it would be very useful to be able to isolate libraries into their own child processes, greatly reducing the scope of possible security holes. I want to write a generic method for doing this simply, efficiently, and transparently. Can you assess my ideas and/or give me other ideas? For method calls, one option would be to generate an RPC interface for each library. This seems doable, but methods involving pointers to large amounts of data may be an issue. I could wrap pointers in buffers, but dynamic argument sizes and limits on RPC argument sizes could be an issue. I could maybe use a packet stream. This would fix some issues, and would remove the need for an individual RPC interface for each library, however the packet stream might need to be fairly large. I might be able to use the RPC idea above, but wrap each pointer in a dataspace. Is this possible? And is it efficient?

3 13

VFS FIFO plugin
by Nobody III 16 Mar '18

16 Mar '18

I've started writing a (single-file) FIFO VFS plugin. I have gotten it to compile, but I still need a little help. How should I test my plugin? I'm not aware of a good run script to base a test on. How should I register signal handlers? I can use a list of List_element<Signal_context_capability>, but that requires extra dynamic memory allocations. How should I handle this to properly account for memory?

1 0

how to use genode on riscv
by Dd Nirvana 16 Mar '18

16 Mar '18

Hi guys, I am so glad to know that genode has supported RISCV from v16.02. I have already read the article(http://genode.org/documentation/articles/riscv) which introduce how genode port the RISCV. However, I am still a little confused about how to build a runnable genode image and how to run it on riscv platform like spike. Could you give me any advices to do it? Thanks a lot! Dong Du

2 2

Genode affinity, multi-core separation and service encapsulation (core inferences)
by Daniel Krefft 15 Mar '18

15 Mar '18

Hello, after an exhaustive evaluation of different scenarios for testing the coherent execution of components on distinct cores, the following question arises: Is it basically possible to separate a component running on core 1 completely (e.g. pd, ram, rom, log) from the remaining system running on core 0? Our results so far demonstrate that, in any case, a component running on core 1 utilizes at least the rom and log services provided by init which is running on core 0. Also the usage of a second level init component (which is suggested by the genode book) didn't change the resulting behavior. Of course, genode is not meant to be a separation kernel by design, but would it still be possible to map/assign resources/partitions to corresponding cores? Or do all components running on different cores still have to contact the genode CORE component which is running on core 0? Best regards Daniel -- Daniel Krefft MSc. Wissenschaftlicher Mitarbeiter Technische Universitaet Muenchen Fakultaet fuer Informatik Lehrstuhl fuer Betriebssysteme Arcisstrasse 21 80333 Muenchen Tel. +49 89 289 18791 daniel.krefft@...256... www.os.in.tum.de/personen/krefft

4 6

base-linux IRQ session
by Johannes Kliemann 14 Mar '18

14 Mar '18

Hi all, I'm currently implementing the IRQ session on base-linux. If I understood the Foundations book correctly interrupts are waiting in a separate thread that locks when it is waiting and continues (and calls the handler) once an interrupt is triggered. According to this I have implemented a kernel module [1] that triggers interrupts via reads on a device file. The interrupt can be registered via ioctl on the file descriptor and the a blocking read is called that returns once the registered interrupts has been triggered. I have looked into the implementations of base-nova and base-hw but didn't completely understand it. As far as I understood the session component implements the session and only requires the interrupt number and a signal handler. The Irq_object implements the waiting thread but I didn't see where it is waiting for the interrupt. Also as far as I could see it the actual interrupt capability stays inside the session in core and only the signal handler capability is passed to the component. Is my understanding of this correct? And is there any further documentation on this? Regards, Johannes [1]: https://github.com/jklmnn/hwiodev/blob/c445eb58daa6d29e9f779bf6ad4b00818fba…

3 3

std::stream::ignore ()
by Stefan 14 Mar '18

14 Mar '18

Hi there, currently I’m porting software for test purposes to the Genode OS. While trying to port OSG, I found out, that std::istream::ignore (long) seems to be missing. Is there an official workaround for this? Thank you very much! Stefan

2 1

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

Sculpt not accepting input from touchpad
by Nobody III 13 Mar '18

13 Mar '18

When I run the Sculpt scenario on my laptop, the touchpad doesn't work, unlike in the old Turmvilla scenario. How can I fix this?

2 2

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users March 2018