Hardware Information

• Several of the other entries in the /proc file system provide access to information about the system hardware.
• CPU Information; /proc/cpuinfo contains information about the CPU or CPUs.
  • The Processor field lists the processor number; this is 0 for single-processor systems.
  • The Vendor, CPU Family, Model, and Stepping fields enable you to determine the exact model and revision of the CPU.
  • More useful, the Flags field shows which CPU flags are set, which indicates the features available in this CPU. For example, mmx indicates the availability of the extended MMX instructions.
  • The last element, bogomips, is a Linux-specific value. It is a measurement of the processor's speed spinning in a tight loop and is therefore a rather poor indicator of overall processor speed.
• Device Information; the /proc/devices file lists major device numbers for character and block devices available to the system.
• PCI Bus Information; the /proc/pci file lists a summary of devices attached to the PCI bus or buses. These are actual PCI expansion cards and may also include devices built into the system's motherboard, plus AGP graphics cards.
• Serial Port Information; the /proc/tty/driver/serial file lists configuration information and statistics about serial ports. For example, this line from /proc/tty/driver/serial might describe serial port 1 (which would be COM2 under Windows).
• DMA Information; the /proc/dma file lists which DMA channels have been reserved by drivers and the name the driver gave when reserving them. The cascade entry is for the DMA line that is used to cascade the secondary DMA controller off of the primary controller; this line is not available for other use.
• Interrupt Information; /proc/interrupts file has one line per reserved interrupt.
  • The fields are the interrupt number, the number of interrupts received on that line, a field that may have a plus sign (SA_INTERRUPT flag set) and the name a driver used when registering that interrupt.
  • The function get_irq_list() in /usr/src/linux/arch/i386/kernel/irq.c (assuming Intel platform) generates this data.
  • This is a very handy file to manually "cat" before installing new hardware, as are /proc/dma and /proc/ioports. They list the resources that are currently in use (but not those used by hardware for which no driver is loaded).
• IOPorts Information; /proc/ioports file lists the various I/O port ranges registered by various device drivers such as your disk drives, ethernet, and sound devices.
• Raid Devices; textbf/proc/mdstat file contains information on raid devices controlled by the md device driver.
• Memory Information; /proc/meminfo file gives information on memory status and is used by the free program. Its format is similar to that displayed by free. This displays the total amount of free and used physical and swap memory in the system. This also shows the shared memory and buffers used by the kernel.
• Clock Information; /proc/rtc file gives information on the hardware real-time clock including the current date and time, alarm setting, battery status, and various features supported. The /sbin/hwclock command is normally used to manipulate the real-time clock.
• Net Information; /proc/net subdirectory contains files that describe and/or modify the behavior of the networking code. Many of these special files are set or queried through the use of the arp, netstat, route, and ipfwadm commands.
• SCSI Information; /proc/scsi subdirectory contains one file that lists all detected SCSI devices and one directory for each controller driver, with a further subdirectory for each separate instance of that controller installed.