{
    "mode": "man",
    "parameter": "port",
    "section": "4",
    "url": "https://www.chedong.com/phpMan.php/man/port/4/json",
    "generated": "2026-10-07T16:42:38Z",
    "sections": {
        "NAME": {
            "content": "mem, kmem, port - system memory, kernel memory and system ports\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "/dev/mem  is a character device file that is an image of the main memory of the computer.  It\nmay be used, for example, to examine (and even patch) the system.\n\nByte addresses in /dev/mem are interpreted  as  physical  memory  addresses.   References  to\nnonexistent locations cause errors to be returned.\n\nExamining  and  patching is likely to lead to unexpected results when read-only or write-only\nbits are present.\n\nSince Linux 2.6.26, and depending on the architecture, the CONFIGSTRICTDEVMEM  kernel  con‐\nfiguration  option limits the areas which can be accessed through this file.  For example: on\nx86, RAM access is not allowed but accessing memory-mapped PCI regions is.\n\nIt is typically created by:\n\nmknod -m 660 /dev/mem c 1 1\nchown root:kmem /dev/mem\n\nThe file /dev/kmem is the same as /dev/mem, except that the kernel virtual memory rather than\nphysical memory is accessed.  Since Linux 2.6.26, this file is available  only  if  the  CON‐\nFIGDEVKMEM kernel configuration option is enabled.\n\nIt is typically created by:\n\nmknod -m 640 /dev/kmem c 1 2\nchown root:kmem /dev/kmem\n\n/dev/port is similar to /dev/mem, but the I/O ports are accessed.\n\nIt is typically created by:\n\nmknod -m 660 /dev/port c 1 4\nchown root:kmem /dev/port\n",
            "subsections": []
        },
        "FILES": {
            "content": "/dev/mem\n/dev/kmem\n/dev/port\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "chown(1), mknod(1), ioperm(2)\n\nLinux man-pages 6.7                          2023-10-31                                       mem(4)",
            "subsections": []
        }
    },
    "summary": "mem, kmem, port - system memory, kernel memory and system ports",
    "flags": [],
    "examples": [],
    "see_also": [
        {
            "name": "chown",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/chown/1/json"
        },
        {
            "name": "mknod",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/mknod/1/json"
        },
        {
            "name": "ioperm",
            "section": "2",
            "url": "https://www.chedong.com/phpMan.php/man/ioperm/2/json"
        }
    ]
}