9.2. Information on The Hardware

Apart from the directories associated to the different processes, /proc also contains a myriad of information on the hardware present in your machine. A list of files from the /proc directory gives the following:

$ ls -d [a-z]*
apm      dma          interrupts  loadavg  mounts      rtc       swaps
bus/     fb           ioports     locks    mtrr        scsi/     sys/
cmdline  filesystems  kcore       meminfo  net/        self/     tty/
cpuinfo  fs/          kmsg        misc     partitions  slabinfo  uptime
devices  ide/         ksyms       modules  pci         stat      version
$

For example, if we look at the contents of /proc/interrupts, we can see that it contains the list of interrupts currently used by the system, along with the peripheral which holds them. Similarly, ioports contains the list of input/output address ranges currently busy, and lastly dma does the same for DMA channels. Therefore, in order to chase down a conflict, look at the contents of these three files:

$ cat interrupts CPU0 0: 127648 XT-PIC timer 1: 5191 XT-PIC keyboard 2: 0 XT-PIC cascade 5: 1402 XT-PIC xirc2ps_cs 8: 1 XT-PIC rtc 10: 0 XT-PIC ESS Solo1 12: 2631 XT-PIC PS/2 Mouse 13: 1 XT-PIC fpu 14: 73434 XT-PIC ide0 15: 80234 XT-PIC ide1 NMI: 0 $ cat ioports 0000-001f : dma1 0020-003f : pic1 0040-005f : timer 0060-006f : keyboard 0070-007f : rtc 0080-008f : dma page reg 00a0-00bf : pic2 00c0-00df : dma2 00f0-00ff : fpu 0170-0177 : ide1 01f0-01f7 : ide0 0300-030f : xirc2ps_cs 0376-0376 : ide1 03c0-03df : vga+ 03f6-03f6 : ide0 03f8-03ff : serial(auto) 1050-1057 : ide0 1058-105f : ide1 1080-108f : ESS Solo1 10c0-10cf : ESS Solo1 10d4-10df : ESS Solo1 10ec-10ef : ESS Solo1 $ cat dma 4: cascade $

Or, more simply, use the lsdev command, which gathers information from these three files and sorts them by peripheral, which is undoubtedly more convenient[1]:

$ lsdev
Device            DMA   IRQ  I/O Ports
------------------------------------------------
cascade             4     2
dma                          0080-008f
dma1                         0000-001f
dma2                         00c0-00df
ESS                          1080-108f 10c0-10cf 10d4-10df 10ec-10ef
fpu                      13  00f0-00ff
ide0                     14  01f0-01f7 03f6-03f6 1050-1057
ide1                     15  0170-0177 0376-0376 1058-105f
keyboard                  1  0060-006f
Mouse                    12
pic1                         0020-003f
pic2                         00a0-00bf
rtc                       8  0070-007f
serial                       03f8-03ff
Solo1                    10
timer                     0  0040-005f
vga+                         03c0-03df
xirc2ps_cs                5  0300-030f
$

An exhaustive listing of files would be too long, but here's the description of some of them:

• cpuinfo: this file contains, as its name says, information on the processor(s) present in your machine.

• modules: this file contains the list of modules currently used by the kernel, along with the usage count for each one. In fact, this is the same information as what is reported by the lsmod command.

• meminfo: this file contains information on memory usage at the time you print its contents. A more clearly formatted output of the same information is available with the free command.

• apm: if you have a laptop, displaying the contents of this file allows you to see the state of your battery. You can see whether the AC is plugged in, the current load of your battery, and if the APM BIOS of your laptop supports it (unfortunately this is not the case for all), the remaining battery life in minutes. The file isn't very readable by itself, therefore you want to use the apm command instead, which gives the same information in a human readable format.

• bus: this subdirectory contains information on all peripherals found on different buses in your machine. Information inside it are generally seldom readable, and for the most part they are dealt with and reformatted with external utilities: lspcidrake, lspnp, etc.