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Search found 13 results on 1 pages for 'chmike'.

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• How to switch to a generic kernel in a headless Ubuntu Server 12.04?

  - by chmike

  I just got a dedicated server with Ubuntu 12.04 installed with a custom compiled kernel. Since I would like to install VirtualBox and this custom kernel doesn't support dynamic module loading (for security) I need to change the kernel. I'm running some Ubuntu servers for years but never palyed with grub and a headless computer. When the command update-grub is run it shows the different kernel it finds. Here is what I see Generating grub.cfg ... Found linux image: /boot/bzImage-3.2.13-xxxx-grs-ipv6-64 Found linux image: /boot/vmlinuz-3.2.0-34-generic Found initrd image: /boot/initrd.img-3.2.0-34-generic No volume groups found done The first one is the active one as seen with uname -r. To me it looks like the second kernel is the one I should use. But I don't know how to configure grub2 to use it. The computer is also configured with a software RAID using mdadm I guess. Never used that before. I don't know if playing with the grub of changing kernel could brake this. What must I do to set the generic kernel as the default one so that I can get VirtualBox running.

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• How to install CUPS 1.6.3 on Ubuntu 13.04

  - by chmike

  We have a CUPS server 1.3 and my freshly installed Ubuntu 13.04 PC has CUPS client 1.6.2. They are incompatible. On the CUPS web server I saw that CUPS 1.6.3 has fixed the issue. "CUPS 1.6.3 fixes some compatibility issues with servers running CUPS 1.3.12 or older..." So I would like to replace CUPS 1.6.2 with 1.6.3 on my Ubuntu 13.04 PC. I guess Ubuntu 13.10 will have CUPS 1.6.3 and later I would like to upgrade from 13.04 to 13.10. I would thus prefer avoiding installing CUPS 1.6.3 manually to avoid any troubles. Is there a way to install CUPS version 1.6.3 using a ppa or something like that ?

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• Windows7 access to Printer shared with XP ?

  - by chmike

  I have, at home, an eeebox running with XP 24/24 with an attached printer (Canon IP5300) installed as shared. We have a few other laptops and PC, all with vista, that can access and print on the shared printer without problem. We just received a new Dell computer with Windows7-64 on it, but it fails to connect the shared printer. I tried connecting the printer with its USB cord directly to the Windows7 PC and the required driver was automatically downloaded and installed. I could then access the printer specific properties, etc. But if I connect it back to the XP computer, the windows7 PC still refused to connect to the remote printer although it now have the drivers. The windows7 is a family pack. By the way, I also have an old canon scanner still perfectly working with XP, but for which I can't find compatible drivers for windows 7. Do I have to buy a new one ? Any help would be welcome.

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• Using Git with shared (symbolic link) directories

  - by chmike

  I'm working on a big Qt application with multiple widgets which are quite complex. One of this widget is a webcam stream viewer. The application is organized so that each program module (i.e. widgets) is stored in its own directory with a .pri file. All these are stored in one main directory grouping all the widget directories. Next to this main project directory I also have application directories. Let say one for each widget. In these directory I have a symbolic link (alias on windows) to the module directory in the main project folder. This application has then the necessary code to build a standalone application showing only the widget. So for instance I have a webcam viewer application, another to control some devices, etc. This source code organization works well and allows me to develop and test the widgets in independent applications while sharing the code with the main application. Currently only the main project directory is under version control using subversion. Now I would like to start using git and would like to know if this shared directory model would work with it or if there is a better way to do it.

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• Use of Curve25519

  - by chmike

  I'm currently investigating the use of curve25519 for signing. Original distribution can be obtained here and a C code implementation here or here. Bernstein suggest to use ECDSA for this but I could not find any code.

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• Unexpected output of std::wcout << L"élève"; in Windows Shell

  - by chmike

  While testing some functions to convert strings between wchar_t and utf8 I met the following weird result with Visual C++ express 2008 std::wcout << L"élève" << std::endl; prints out "ÚlÞve:" which is obviously not what is expected. This is obviously a bug. How can that be ? How am I suppose to deal with such "feature" ?

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• Dynamic binding in C++

  - by chmike

  I'm implementing a CORBA like server. Each class has remotely callable methods and a dispatch method with two possible input, a string identifying the method or an integer which would be the index of the method in a table. A mapping of the string to the corresponding integer would be implemented by a map. The caller would send the string on the first call and get back the integer with the response so that it simply has to send the integer on subsequent calls. It is just a small optimization. The integer may be assigned dynamically on demand by the server object. The server class may be derived from another class with overridden virtual methods. What could be a simple and general way to define the method binding and the dispatch method ?

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• Modifying an image with OpenGL ?

  - by chmike

  I have a device to acquire XRay images. Due to some technical constrains, the detector is made of heterogeneous pixel size and multiple tilted and partially overlapping tiles. The image is thus distorted. The detector geometry is known precisely. I need a function converting these distorted images into a flat image with homogeneous pixel size. I have already done this by CPU, but I would like to give a try with OpenGL to use the GPU in a portable way. I have no experience with OpenGL programming, and most of the information I could find on the web was useless for this use. How should I proceed ? How do I do this ? Image size are 560x860 pixels and we have batches of 720 images to process. I'm on Ubuntu.

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• How to control virtual memory management in linux?

  - by chmike

  I'm writing a program that uses an mmap file to hold a huge buffer organized as an array of 64 MB blocks. The blocks are used to aggregate data received from different hosts through the network. As a consequence the total data size written in each block is not known in advance. Most of the time it is only 2MB but in some cases it can be up to 20MB or more. The data doesn't stay long in the buffer. 90% is deleted after less than a second and the rest is transmitted to another host. I would like to know if there is a way to tell the virtual memory manager that ram pages are not dirty anymore when data is deleted. Should I use mmap and munmap when a block is used and released to control the virtual memory ? What would be the overhead of doing this ? Also, some colleagues expressed concerns about the performance impact of allocating such a big mmap space. I expect it to behave like a swap file so that only dirty pages are to be considered.

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• Is select() Ok to implement single socket read/write timeout ?

  - by chmike

  I have an application processing network communication with blocking calls. Each thread manages a single connection. I've added a timeout on the read and write operation by using select prior to read or write on the socket. Select is known to be inefficient when dealing with large number of sockets. But is it ok, in term of performance to use it with a single socket or are there more efficient methods to add timeout support on single sockets calls ? The benefit of select is to be portable.

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• C++ : Initializing base class constant static variable with different value in derived class ?

  - by chmike

  I have a base class A with a constant static variable a. I need that instances of class B have a different value for the static variable a. How could this be achieved, preferably with static initialization ? class A { public: static const int a; }; const int A::a = 1; class B : public A { // ??? // How to set *a* to a value specific to instances of class B ? };

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• Is select() Ok to implemnet single socket read/write timeout ?

  - by chmike

  I have an application processing network communication with blocking calls. Each thread manages a single connection. I've added a timeout on the read and write operation by using select prior to read or write on the socket. Select is known to be inefficient when dealing with large number of sockets. But is it ok, in term of performance to use it with a single socket or are there more efficient methods to add timeout support on single sockets calls ? The benefit of select is to be portable.

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• Portable way to get file size in C/C++

  - by chmike

  I need to determin the byte size of a file. The coding language is C++ and the code should work with Linux, windows and any other operating system. This implies using standard C or C++ functions/classes. This trivial need has apparently no trivial solution.

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