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2353 discussions

Experiences
by Peter Nguyen 14 Apr '10

14 Apr '10

Hi, I was asked to summarize my experiences with using shared memory in Genode. Apologies for the extremely late reply. My project involves implementing a profiling infrastructure, whereby i have a profiling server that coordinates the execution of profiling ie. the collection and processing of samples. Samples are to be collected from a range of sources, where the samples generated are analysed by the profiling server. The issue I was having was the sharing of memory between the profiling server and the component where the samples were being generated. Via regular communication with the Genode developers, I got to reading up on the use of Dataspaces as the mechanism for sharing data between two components. Essentially, memory sharing between components is achieved by creating a dataspace, where a memory region is defined such that data written to this memory is shared. The actual sharing occurs by having a component (in this case a client) establish a connection to the server, which allocates the dataspaces. In my profiling design, a sampling buffer that is shared between a client and a server is only relevant to that connection only ie. other components do not really need to know about this data. To illustrate this, i will use a diagram that Christian used in helping me with establishing data sharing between components: Address | Dataspaces and Sharing spaces | ---------------------------------------------- ---------------------------------------------- Sampling | Sample Sample Server | buffer A buffer B ---------------------------------------------- Sampled | Sample - client A | buffer A - ---------------------------------------------- Sampled | - Sample client B | - buffer B In the above diagram, the data generated in "Sampled client A" has no relevance whatsoever to "Sampled client B". Hence, I don't need to worry about Sampled client A and Sampled client B having to share its profiling data with each other (i'm sure there might be cases where such sharing is to occur, for instance, if the intention is to write sampling data to the same buffer). The motivation for this design is that each sampling buffer represents a particular part of the system being profiled. For example, Sampled client A could represent a HTTP server for profiling network activity, and Sampled client B could represent a kernel buffer to obtain CPU samples. I could then have another sampled client that measures the rate at which Genode threads are being created (there obviously might be better examples of another client). Sample processing is then performed by the server, via a language I have implemented (the code gets converted to C++ code). The client-server approach that Genode motivates makes the profiling environment easily extensible because the creation of a sampling buffer simply involves having the client to be sampled establish a connection to the profiling server (I have a connection.h file as part of the sampling_session interface, which I learned about from the hello world tutorial). After declaring the connection to the profiling server, a dataspace capability is obtained from this connection and from there, the dataspace is attached to the client's local address space, which results in data sharing now working. The code snippet below should illustrate what I just explained. Sampling::Connection samp; Dataspace_capability ds = samp.get_cap(); void *ptr = Genode::env()->rm_session()->attach(ds); I can then write data via *ptr, knowing that the data is shared with the profiling server. So i've probably gone all over the place with this email, but hopefully someone might get something out of this. Peter

2 2

Shared library
by Peter Nguyen 11 Mar '10

11 Mar '10

Hi, I've tried to create a shared library for use by multiple components in Genode, where in the mk file for the library, i have specified SHARED_LIB=yes. When i try to execute Genode, I keep getting the following message at runtime: "Dynamically linked file found, but no dynamic linker binary present" What steps do i need to take so as to ensure that the binary is present? Peter

4 16

OKL4 build errors
by Peter Nguyen 02 Mar '10

02 Mar '10

Hi, In upgrading to Genode 10.02, i'm encountering build errors when i specifically include one of three L4 header files, namely thread.h, ipc.h, and arch/thread.h. I do the #include statements within a namespace declaration like so: namespace Okl4 { extern "C" { //includes }} Every time i try to build OKL4, i keeping getting the following error which is related to utcb.h: error: expected unqualified-id before ‘[’ token Does anyone have any idea as to why this is happening? If i don't include any of those files, my code builds fine. Peter

3 3

Support for other (ARM) machines
by Thomas DuBuisson 02 Mar '10

02 Mar '10

After getting Genode to build for GTA01 I'm now interested in getting a build running on hardware I have available (an OMAP3 / beagleboard based ARM system). Are there notes somewhere on adding machine support to Genode or should I just study anywhere that mentions gumstix or GTA01? Cheers, Thomas

2 1

Further questions about LWIP/HTTP server
by Peter Nguyen 01 Mar '10

01 Mar '10

Hi, In digging to the HTTP server functionality, I noticed that with IP address, data is stored for local and remote IP addresses. I gather remote IPs refer to the machines making the requests. Does the local IP refer to the HTTP server itself?? Peter

3 4

Method Ram_session_component::alloc()
by Frank Kaiser 01 Mar '10

01 Mar '10

Hello There is a small glitch in the given method found in file base/src/core/ram_session_component.cc: 1. In line 141 a new Dataspace_component is generated and assigned to pointer *ds. 2. In line 144 the pointer is used to call method _clear_ds() (defined for instance in file base-okl4/src/core/ram_session_support.cc). There (line 44) pointer *ds is dereferenced w/o any validity check. 3. In line 146 a null pointer check is applied on *ds. If the new operator in line 141 is expected to return NULL in some cases, then the null pointer check in line 146 should precede the usage of the pointer in line 144, otherwise the code of line 146ff would be obsolete. Frank

2 1

Adding a new library
by Peter Nguyen 25 Feb '10

25 Feb '10

Hi, I'm now trying to add my own library, and have tried adding the files as part of 'base'. Every time I try to build Genode, i keep getting messages pertaining to undefined references to functions that i have implemented. How do i go about incorporating the files i've written as part of 'base'? I'm sure i've missed something.... Thanks Peter

2 2

The new release 10.02 of the Genode OS Framework is available
by Norman Feske 24 Feb '10

24 Feb '10

The release 10.02 again broadens the field of applications for Genode by introducing support for two new kernels: the Codezero kernel and the NOVA hypervisor. The former is primarily targeted at ARM platforms, the latter at x86 virtualization. Moreover, we introduced a management concept for real-time priorities within the framework's API, which can be used in conjunction with the real-time schedulers of the L4ka::Pistachio and OKL4 kernels. Beside many improvements and refinements of the existing parts of the framework, we incorporated the initial port of the Python script interpreter into this release. Release-notes summary for version 10.02 --------------------------------------- * Platform support * NOVA hypervisor * Codezero kernel * New thread-context management * Real-time priorities * Python scripting You can find the complete release notes for the version 10.02 here: http://genode.org/documentation/release-notes/10.02/ The new release is available via the project's subversion repository and at the Genode download page: http://genode.org/download/latest-release Regards -- Norman Feske Genode Labs http://www.genode-labs.com · http://genode.org Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth

1 0

Building lwip
by Peter Nguyen 22 Feb '10

22 Feb '10

Hi, I'm trying to build the lwip test so that I can make a start on experimentation. However, I keep on getting build errors. To build this package, I included the libports package, and also the libc package. However, I keep getting errors about how size_t hasn't been declared in scope. I also tried including my own definition for size_t, but other errors result. What is the correct way of building the lwip package? Peter

5 15

race in oklinux/contrib/arch/l4/kernel/sys_genode.c
by Sven Fülster 17 Feb '10

17 Feb '10

Hi all, you have a race condition in oklinux/contrib/arch/l4/kernel/sys_genode.c resp. oklx_genode.patch lines 1894..1905 #ifdef CONFIG_FB_GENODE + if(genode_input_initialized()) + { + /* Put the input events into our framebuffer driver */ + num = genode_input_flush(); + for(i=0;i<num;i++) { + genode_input_event(i, genode_fb_mouse_event, genode_fb_key_event); + } + } +#endif //CONFIG_FB_GENODE + + genode_lock(timer_main_kernel_lock); which shows up under heavy load (freezing Xfbdev, raising some BUG()s or a pagefault in update_stats_wait_end). Moving the input polling into the critical section solved the problem here: + genode_lock(timer_main_kernel_lock); + #ifdef CONFIG_FB_GENODE + if(genode_input_initialized()) + { + /* Put the input events into our framebuffer driver */ + num = genode_input_flush(); + for(i=0;i<num;i++) { + genode_input_event(i, genode_fb_mouse_event, genode_fb_key_event); + } + } +#endif //CONFIG_FB_GENODE Cheers Sven -- Sven FÃ¼lster

2 1

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