Re: /dev/io , /dev/mem : only used by Xorg?

From: Kris Kennaway (kris_at_obsecurity.org)
Date: 02/28/05

  • Next message: Kris Kennaway: "Re: Deleting orphaned ports" 
    Date: Mon, 28 Feb 2005 02:57:50 -0800
To: Ted Mittelstaedt <tedm@toybox.placo.com>

    On Mon, Feb 28, 2005 at 01:32:26AM -0800, Ted Mittelstaedt wrote:

    > Instead, they are part of the kernel itself.
    >
    > All the /dev files are, /dev/random, /dev/ad0 and so on, are simple
    > files that take up only a few bytes of space. They are convenient
    > "hook points" to use to get to these devices. That is, when a program
    > accesses /dev/random, it isn't actually opening that file. Instead,
    > the kernel intercepts that call and supplies the program opening
    > that device with the output of the actual device.
    >
    > This is why these device files are created with the mknod utility,
    > rather than just copying a file to /dev/random - since doing that is
    > accessing the device, not creating the device file.
    >
    > So, deleting these /dev devices saves you practically no space at
    > all, and does not in fact delete the devices - it only deletes the
    > access point to them. The devices are still there in the kernel.

    No, in 5.x the device nodes are created automatically by devfs and
    only appear in /dev by default if support is enabled in the kernel.
    As the original poster discussed, /dev/io, /dev/mem and /dev/random
    are optional components of the 5.x kernel, although as I replied, the
    situations in which one would not want to include them are limited.

    Kris

  • Next message: Kris Kennaway: "Re: Deleting orphaned ports"

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