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race-condition in ram_fs and fs_query?
by Guido Witmond 27 May '19

27 May '19

Hi Genodians, I'm working on my HnH19-project to create a component listening on a shared filesystem to open each pdf file into a separate instance of mupdf. Goal is to tie the share to a linux-vm in vbox so firefox and thunderbird can have a simple 'cp' command to get pdfs rendered outside that vm. I add a RAM-FS, FS-QUERY and REPORT-ROM to mupdf.run. The file gets put in the ram-fs, fs-query should pick that up and report it to the report-rom. <start name="pdf_share"> <binary name="ram_fs"/> <resource name="RAM" quantum="128M"/> <provides> <service name="File_system"/> </provides> <config verbose="yes"> <default-policy root="/" writeable="yes" /> </config> </start> <start name="report_new_pdf"> <binary name="report_rom"/> <resource name="RAM" quantum="1M"/> <provides> <service name="Report"/> <service name="ROM"/> </provides> <config verbose="yes"/> </start> <start name="fs_query"> <resource name="RAM" quantum="1M"/> <config verbose="yes"> <vfs> <fs writeable="yes"/> </vfs> <query path="/" content="yes"/> </config> </start> I change the test-scenario to copy a pdf into the share and start the pdf-viewer. The viewer picks up the pdf and renders it. So far so good. The problem is that while the 'add'-test copies the file, it gets detected by fs_query but fs_query thinks it's gone: [init -> test -> add] --- noux started --- [init -> fs_query] Error: failed to watch '//foo.pdf' [init -> fs_query] Warning: could not obtain content of nonexistent file foo.pdf (The error comes from gems/vfs.h L556, the warning from fs_query/main.cc L80.) Fs_quey does send a new report but does not show the file, it show an empty directory. [init -> report_new_pdf] report 'fs_query -> listing' [init -> report_new_pdf] <listing> [init -> report_new_pdf] <dir path="/"/> [init -> report_new_pdf] </listing> However, a ls -laR shows it's there: [init -> test -> ls-after] /dest: [init -> test -> ls-after] total 1 [init -> test -> ls-after] drwxr-xr-x 0 root 0 0 Jan 1 00:00 . [init -> test -> ls-after] drwxr-xr-x 0 root 0 0 Jan 1 00:00 .. [init -> test -> ls-after] -rwxrwxrwx 0 root 0 8192 Jan 1 00:00 foo.pdf Now the race condition: When I set the fs-query option to show the content to "no", it gives the same error: failed to watch '//foo.pdf' but it now it does send the file name to the report: [init -> report_new_pdf] <file name="foo.pdf"/> So it seems that somehow that fs_query watch learns there is a file while the contents are not yet committed. Accessing that triggers a file-not-found error. Did I discover a race condition or am I doing something wrong? With regards, Guido. PS. I added the complete run-file and logs for completeness. (log-1 shows the contents-flag to no). PPS. I'm testing with Qemu in a linux VM on my AMD nixos host.

3 6

mouse pointer doesn't work on Rpi 1
by kimberly nNA 23 May '19

23 May '19

Dear Genode team, I am Kimbelly. I tried this commands : $ ./tool/create_builddir rpi $ make run/demo KERNEL=hw I could run the demo on Rpi 1 B+ (ARM v6) but the mouse pointer didn't work. I don't know what happen... (I have uncommented the dde_linux) Another question is now what kind of the ARM boards that you recommend ? Thanks a lot ! 😊

2 1

Pre 19.05 compiler warnings "this statement may fall through"
by Duss Pirmin 22 May '19

22 May '19

Hello Genodians While testing the update to Genode 19.05 I recognized many "this statement may fall through" warnings. I have created patches for the following files: base/include/util/string.h base/include/util/arg_string.h The patches are located at: https://github.com/trimpim/genode/tree/gcc8.3_fall_through_warnings Feel free to pick them up, if you like. Best regards, Pirmin

1 0

pre 19.05 feedback: libc port update breaks mkfs from e2fsprogs
by Duss Pirmin 21 May '19

21 May '19

Hello Genodians I'm running preparations for the transition to Genode 19.05. mkfs.run from https://github.com/trimpim/genode/tree/test-19.05-mkfs_fails fails with the error message (KERNEL=nova): "/dev/block: Memory allocation failed while setting up superblock". Through bisecting I determined, that the libc port update seems to be the cause of the problem. a55af1828 last working commit dd5aa1748 .. 057a8b0b3 build fails 132ef4dcb compiles, test fails The error occurs in line 76 in the file src/noux-pkg/e2fsprogs/lib/ext2fs/inline.c of the contrib code. Best regards Pirmin

2 1

Interesting paper on breaking down OS-abstractions
by Guido Witmond 03 May '19

03 May '19

Hi Genodians, Today I came across this paper[1] on the slowdown from POSIX and other kernel abstractions. It offers the notion of a parakernel to break down the monolithic kernel and take kernel abstractions out of the data path. It seems that Genode, although not a parakernel, is quite well adapted to this. Not by accident, I think ;-) It's discussed at [2] 1: https://penberg.org/parakernel-hotos19.pdf 2: https://news.ycombinator.com/item?id=19818899

1 0

usb_drv error -92 for RPi | Genode 18.05 with Fiasco.OC 79
by Alexander Weidinger 18 Apr '19

18 Apr '19

Hello everyone, when executing 'lwip' on the RPi 2, I get the following output for the usb_drv: > [init -> usb_drv] dev_info: DWC OTG Controller > [init -> usb_drv] dev_info: new USB bus registered, assigned bus number 1 > [init -> usb_drv] dev_info: irq 9, io mem 0x00000000 > [init -> usb_drv] dev_info: USB hub found > [init -> usb_drv] dev_info: 1 port detected > [init -> usb_drv] dev_info: new high-speed USB device number 2 using dwc_otg > [init -> usb_drv] dev_error: device descriptor read/all, error -92 > [init -> usb_drv] dev_info: new high-speed USB device number 3 using dwc_otg > [init -> usb_drv] dev_error: device descriptor read/all, error -92 > [init -> usb_drv] dev_info: new high-speed USB device number 4 using dwc_otg > [init -> usb_drv] dev_error: device descriptor read/8, error -92 > [init -> usb_drv] dev_error: device descriptor read/8, error -92 > [init -> usb_drv] dev_info: new high-speed USB device number 5 using dwc_otg > [init -> usb_drv] dev_error: device descriptor read/8, error -92 > [init -> usb_drv] dev_error: device descriptor read/8, error -92 > [init -> usb_drv] dev_error: unable to enumerate USB device Does anyone have an idea what I can do, to get the Ethernet adapter working? Any help is appreciated! I don't really understand the problem here, since the driver works flawlessly for the RPi 1 B+ (using foc_rpi as platform) - which uses the same chip as the RPi 2 (SMSC LAN9514). My Genode version [2] and Fiasco.OC version [3]. To the backstory: ----------------- I am currently in the process of "porting" Fiasco.OC/Genode to the Raspberry Pi 2 (Model B). As a basis I use Genode in the version 18.05 and Fiasco.OC in the version 79. I created a new device, the rpi2, and based it on the already available rpi model. The main changes I did for the rpi2 platform [1] are - the different arm architecture - from armv6 to armv7a in a few files - the different physical base address - from 0x2000:0000 to 0x3f00:0000 - a RAM size of 1008 MB starting at 0x0000:0000 (1024 MB - 16 MB for peripherals) I use version 79 of the Fiasco.OC kernel since it adds support for the three different BCM283X platforms. In order to get version 79 of the kernel running with Genode, I used the official 79 as a basis and cherry-picked commits from Genode's version of Fiasco.OC (72). [0] My setup works completely fine for the RPi 1 (Model B+), even for the usb/nic driver. As the RPi 1 (Model B+) makes use of the SMSC LAN9514, instead of the SMSC LAN9512 (used in RPi Model B) it should also work for the RPi 2 (Model B), since this SBC also uses the SMSC LAN9514. [0] https://github.com/skalk/foc/commits/r72 [1] https://github.com/irgendwie/genode/commits/foc-rpi2 [2] https://github.com/irgendwie/genode/tree/foc-rpi2 [3] https://github.com/irgendwie/foc/tree/genode-r79-rpi2 ----------------- Best regards Alexander

5 15

Heads-up about pending block-API changes
by Norman Feske 16 Apr '19

16 Apr '19

Hello everyone, hereby, I'd like to raise your awareness about pending API changes that affect block-level components. I post this here because block-level components outside our source tree will need an adaptation to the new API. The change consists of two parts, one for the server side and one of the client side. Both parts are already on our staging branch and will reach the master branch soon. The new server-side API is located at 'os/include/block/request_stream.h'. It is already part of Genode 19.02 but remained largely unused at the point of the release. In contrast to the traditional API at 'os/include/block/component.h', the new API anticipates the design of block services as state machines and is designed for the efficient batched processing of block operations. You can find an illustrative example of a block server using this API at 'os/src/test/block_request_stream'. The new client-side API has become part of the 'Block::Connection' located in 'os/include/block_session/connection.h'. Like the server-side API, it is designed for an asynchronous and batched mode of operation. It achieves this with the added notion of 'Job' objects associated to a connection. For more details, you can find the corresponding issue at [1]. The first component I updated to the new API is the block tester located at 'os/src/app/block_tester/'. So there is already a nice playground in the form of the block_tester.run and block_request_stream.run scripts, both located at 'os/run/'. [1] https://github.com/genodelabs/genode/issues/3283 The client-side as well as the server-side APIs completely hide the underlying packet stream mechanism so that we can - in the future once all components are migrated to the new API - simplify this transport mechanism. By hiding the packet stream, components become much simpler because the application code is no longer bothered with the handling of packet-stream corner cases. If you maintain custom block-level components, I hereby encourage you giving the new API a try and report your findings. At the current time, the original APIs are still maintained. So there can be smooth transition phase. Still, a few cosmetic adaptations even in the case of intermediately sticking to the old API are needed. * 'Block::Connection' has become a template. To make your code compile again, the default template argument may become handy. Just rename the type to 'Block::Connection<>'. * The 'Block::Session::info' RPC function has a new signature. Instead of using C-ish out parameters, the new version returns a compound object of type 'Info'. * The original 'Block::Session::Operations' type is gone. In practice, it was merely used to distinguished read-only from read-writeable block devices. Now, it has been superseded with a 'writeable' attribute of the 'Info' type. Much simpler. * SYNC and TRIM have become first-class asynchronous block operations. The former 'sync' RPC function does not exist anymore. I hope you like the direction for the API changes. Your feedback is very welcome. If this direction turns out well, we may take the design as blue print for other asynchronous inter-component communication APIs (NIC and file system come in mind) in the future. Cheers Norman -- Dr.-Ing. Norman Feske Genode Labs https://www.genode-labs.com · https://genode.org Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth

1 0

Genodians.org Feature Requests
by John J. Karcher 09 Apr '19

09 Apr '19

Hello Genodians, The content on Genodians.org has been so interesting and varied that I worry we might lose valuable content in the sheer volume as time goes by. Here are a couple of ideas that I thought might help (probably already on the "to do" list, but just in case): 1. "Sticky" / "Featured" Posts - Things like the announcement for the latest release, other important news, etc. should probably be kept at/near the top or in a special area. 2. Search / Filter Tags - I think it would be helpful to add "tags" to the posts to make it easier to find items on a certain subject. I would recommend defining the format and adding the tag data as soon as possible, even if the feature isn't implemented for a while - it's always harder to go back over a lot of data than to enter it as the records are added. Just food for thought... Thanks! -- John J. Karcher devuser(a)alternateapproach.com

8 12

Genode Corner
by John J. Karcher 08 Apr '19

08 Apr '19

Hello Genodians, Over the last week or so, I slapped together a quick web page I am calling "Genode Corner", which is an attempt at a very simple community site for Genode users: http://www.alternateapproach.com/Computing/Genode/Genode_Corner/index.html Don't expect much. I am not a real web designer, and there is no interactivity at this stage. (It is generated from static XML files using client-side JavaScript.) And there is very little data to start. The point of it is to collect some useful information in one place for easy reference. For instance, I implemented my own feature request of "sticky" Genodians.org articles. ;^) Let me know if anyone sees any value in it. I am considering putting together a simple back-end, using a real database, which could eventually allow interactivity. But the effort I put into it will probably be proportional to the amount of interest. I put an e-mail alias on the bottom of the page to contact me about it. Thanks! -- John J. Karcher devuser(a)alternateapproach.com

2 1

Is anyone else running seL4 on the iMX.6 sabrelite?
by Joel Desermeau 08 Apr '19

08 Apr '19

I have a few noobish questions that I hope someone could answer! - After making a custom boot image, how should I format the sd card and where should I place the image? -How can I get u-boot to boot the image? Thanks :p Joel Desermeau

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