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Parin Sharma

How the Linux kernel works | TuxRadar Linux - 0 views

  • The kernel makes its services available to the application programs that run on it through a large collection of entry points, known technically as system calls.
  • From a programmer's viewpoint, these look just like ordinary function calls, although in reality a system call involves a distinct switch in the operating mode of the processor from user space to kernel space. Together, the repertoire of system calls provides a 'Linux virtual machine', which can be thought of as an abstraction of the underlying hardware.
  • An even less visible function of the kernel, even to programmers, is memory management. Each process runs under the illusion that it has an address space (a valid range of memory addresses) to call its own.
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  • Note that specific application protocols such as FTP, DNS or HTTP are implemented by user-level programs and aren't part of the kernel.
  • the kernel provides a large collection of modules that know how to handle the low-level details of talking to hardware devices - how to read a sector from a disk, how to retrieve a packet from a network interface card and so on. These are sometimes called device drivers.
  • In contrast, modern Linux kernels are modular: a lot of the functionality is contained in modules that are loaded into the kernel dynamically.
  • This keeps the core of the kernel small and makes it possible to load or replace modules in a running kernel without rebooting.
  • This tells modprobe to include the probe_mask=1 option every time it loads the snd-hda-intel module. Some recent Linux distrubutions split this information up into multiple files under /etc/modprobe.d rather than putting it all in modprobe.conf.
Parin Sharma

Linux is NOT Windows !! - 0 views

  • So, to avoid problem #3b: Just remember that what Linux seems to be now is not what Linux was in the past. The largest and most necessary part of the Linux community, the hackers and the developers, like Linux because they can fit it together the way they like; they don't like it in spite of having to do all the assembly before they can use it.
  • So whilst vi has an interface that is hideously unfriendly to new users, it is still in use today because it is such a superb interface once you know how it works. Firefox was created by people who regularly browse the Web. The Gimp was built by people who use it to manipulate graphics files. And so on.
  • However, there is an important difference between a FOSS programmer and most commercial software writers: The software a FOSS programmer creates is software that he intends to use. So whilst the end result might not be as 'comfortable' for the novice user, they can draw some comfort in knowing that the software is designed by somebody who knows what the end-users needs are: He too is an end-user. This is very different from commercial software writers, who are making software for other people to use: They are not knowledgeable end-users.
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  • Functionality comes first. Nobody designs a killer interface and then tries to add functionality bit by bit. They create functionality, and then improve the interface bit by bi
  • t tells us that developers in both camps looked for ways of improving the GUI, and because there are only a limited number of solutions to a problem, they often used very similar methods. Similarity does not in any way prove or imply imitation. Remembering that will help you avoid straying into problem #6 territory.
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