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How to configure the Linux kernel/arch/arm

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Howto configure the Linux kernel / arch / arm


For a description of the syntax of this configuration file,
see Documentation/kbuild/kconfig-language.txt.

"Linux Kernel Configuration"


  • Option: ARM
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y
      The ARM series is a line of low-power-consumption RISC chip designs licensed by ARM ltd and targeted at embedded applications and handhelds such as the Compaq IPAQ. ARM-based PCs are no longer manufactured, but legacy ARM-based PC hardware remains popular in Europe. There is an ARM Linux project with a web page at <http://www.arm.linux.org.uk/>.


  • Option: MMU
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y


  • Option: EISA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
      The Extended Industry Standard Architecture (EISA) bus was developed as an open alternative to the IBM MicroChannel bus.
      The EISA bus provided some of the features of the IBM MicroChannel bus while maintaining backward compatibility with cards made for the older ISA bus. The EISA bus saw limited use between 1988 and 1995 when it was made obsolete by the PCI bus.
      Say Y here if you are building a kernel for an EISA-based machine.
      Otherwise, say N.


  • Option: SBUS
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: MCA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
      MicroChannel Architecture is found in some IBM PS/2 machines and laptops. It is a bus system similar to PCI or ISA. See <file:Documentation/mca.txt> (and especially the web page given there) before attempting to build an MCA bus kernel.


  • Option: UID16
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y


  • Option: RWSEM_GENERIC_SPINLOCK
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y


  • Option: RWSEM_XCHGADD_ALGORITHM
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: GENERIC_CALIBRATE_DELAY
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y


  • Option: GENERIC_BUST_SPINLOCK
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: ARCH_MAY_HAVE_PC_FDC
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: GENERIC_ISA_DMA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: FIQ
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


System TypeEdit

"ARM system type"

    • default ARCH_RPC


  • Option: ARCH_CLPS7500
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Cirrus-CL-PS7500FE
    • select TIMER_ACORN
    • select ISA


  • Option: ARCH_CLPS711X
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) CLPS711x/EP721x-based


  • Option: ARCH_CO285
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Co-EBSA285
    • select FOOTBRIDGE
    • select FOOTBRIDGE_ADDIN


  • Option: ARCH_EBSA110
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) EBSA-110
    • select ISA
      This is an evaluation board for the StrongARM processor available from Digital. It has limited hardware on board, including an onboard Ethernet interface, two PCMCIA sockets, two serial ports and a parallel port.


  • Option: ARCH_CAMELOT
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Epxa10db
      This enables support for Altera's Excalibur XA10 development board. If you would like to build your kernel to run on one of these boards then you must say 'Y' here. Otherwise say 'N'


  • Option: ARCH_FOOTBRIDGE
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) FootBridge
    • select FOOTBRIDGE


  • Option: ARCH_INTEGRATOR
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Integrator
    • select ARM_AMBA
    • select ICST525


  • Option: ARCH_IOP3XX
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) IOP3xx-based
    • select PCI


  • Option: ARCH_IXP4XX
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) IXP4xx-based
    • select DMABOUNCE
    • select PCI


  • Option: ARCH_IXP2000
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) IXP2400/2800-based
    • select PCI


  • Option: ARCH_L7200
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) LinkUp-L7200
    • select FIQ
      Say Y here if you intend to run this kernel on a LinkUp Systems L7200 Software Development Board which uses an ARM720T processor. Information on this board can be obtained at:
      <http://www.linkupsys.com/>
      If you have any questions or comments about the Linux kernel port to this board, send e-mail to <sjhill@cotw.com>.


  • Option: ARCH_PXA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) PXA2xx-based


  • Option: ARCH_RPC
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) RiscPC
    • select ARCH_ACORN
    • select FIQ
    • select TIMER_ACORN
    • select ARCH_MAY_HAVE_PC_FDC
      On the Acorn Risc-PC, Linux can support the internal IDE disk and CD-ROM interface, serial and parallel port, and the floppy drive.


  • Option: ARCH_SA1100
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) SA1100-based
    • select ISA
    • select ARCH_DISCONTIGMEM_ENABLE


  • Option: ARCH_S3C2410
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Samsung S3C2410
      Samsung S3C2410X CPU based systems, such as the Simtec Electronics BAST (<http://www.simtec.co.uk/products/EB110ITX/>), the IPAQ 1940 or the Samsung SMDK2410 development board (and derviatives).


  • Option: ARCH_SHARK
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Shark
    • select ISA
    • select ISA_DMA
    • select PCI


  • Option: ARCH_LH7A40X
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Sharp LH7A40X
      Say Y here for systems based on one of the Sharp LH7A40X System on a Chip processors. These CPUs include an ARM922T core with a wide array of integrated devices for hand-held and low-power applications.


  • Option: ARCH_OMAP
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) TI OMAP


  • Option: ARCH_VERSATILE
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Versatile
    • select ARM_AMBA
    • select ICST307
      This enables support for ARM Ltd Versatile board.


  • Option: ARCH_REALVIEW
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) RealView
    • select ARM_AMBA
    • select ICST307
      This enables support for ARM Ltd RealView boards.


  • Option: ARCH_IMX
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) IMX


  • Option: ARCH_H720X
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Hynix-HMS720x-based
      This enables support for systems based on the Hynix HMS720x


  • Option: ARCH_AAEC2000
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Agilent AAEC-2000 based
    • select ARM_AMBA
      This enables support for systems based on the Agilent AAEC-2000





















Definitions to make life easier


  • Option: ARCH_ACORN
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


bool 'Use XScale PMU as timer source' CONFIG_XSCALE_PMU_TIMER


  • Option: XSCALE_PMU
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • depends on CPU_XSCALE && !XSCALE_PMU_TIMER
    • default y




  • Option: FORCE_MAX_ZONEORDER
    • Kernel Versions: 2.6.15.6 ...
    • depends on SA1111
    • default "9"

Bus supportEdit

  • Option: ARM_AMBA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: ISA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
      Find out whether you have ISA slots on your motherboard. ISA is the name of a bus system, i.e. the way the CPU talks to the other stuff inside your box. Other bus systems are PCI, EISA, MicroChannel (MCA) or VESA. ISA is an older system, now being displaced by PCI; newer boards don't support it. If you have ISA, say Y, otherwise N.


  • Option: ISA_DMA
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)


  • Option: ISA_DMA_API
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y


  • Option: PCI
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) PCI support if ARCH_INTEGRATOR_AP || ARCH_VERSATILE_PB
      Find out whether you have a PCI motherboard. PCI is the name of a bus system, i.e. the way the CPU talks to the other stuff inside your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or VESA. If you have PCI, say Y, otherwise N.
      The PCI-HOWTO, available from <http://www.tldp.org/docs.html#howto>, contains valuable information about which PCI hardware does work under Linux and which doesn't.
Select the host bridge type


  • Option: PCI_HOST_VIA82C505
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • depends on PCI && ARCH_SHARK
    • default y




Kernel FeaturesEdit

  • Option: SMP
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Symmetric Multi-Processing (EXPERIMENTAL)
    • depends on EXPERIMENTAL && REALVIEW_MPCORE
      This enables support for systems with more than one CPU. If you have a system with only one CPU, like most personal computers, say N. If you have a system with more than one CPU, say Y.
      If you say N here, the kernel will run on single and multiprocessor machines, but will use only one CPU of a multiprocessor machine. If you say Y here, the kernel will run on many, but not all, single processor machines. On a single processor machine, the kernel will run faster if you say N here.
      See also the <file:Documentation/smp.txt>, <file:Documentation/i386/IO-APIC.txt>, <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at <http://www.linuxdoc.org/docs.html#howto>.
      If you don't know what to do here, say N.


  • Option: NR_CPUS
    • Kernel Versions: 2.6.15.6 ...

"Maximum number of CPUs (2-32)" 2 32

    • depends on SMP
    • default "4"


  • Option: HOTPLUG_CPU
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Support for hot-pluggable CPUs (EXPERIMENTAL)
    • depends on SMP && HOTPLUG && EXPERIMENTAL
      Say Y here to experiment with turning CPUs off and on. CPUs can be controlled through /sys/devices/system/cpu.


  • Option: LOCAL_TIMERS
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Use local timer interrupts
    • depends on SMP && REALVIEW_MPCORE
    • default y
      Enable support for local timers on SMP platforms, rather than the legacy IPI broadcast method. Local timers allows the system accounting to be spread across the timer interval, preventing a thundering herd at every timer tick.


  • Option: PREEMPT
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Preemptible Kernel (EXPERIMENTAL)
    • depends on EXPERIMENTAL
      This option reduces the latency of the kernel when reacting to real-time or interactive events by allowing a low priority process to be preempted even if it is in kernel mode executing a system call. This allows applications to run more reliably even when the system is under load.
      Say Y here if you are building a kernel for a desktop, embedded or real-time system. Say N if you are unsure.


  • Option: NO_IDLE_HZ
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Dynamic tick timer
      Select this option if you want to disable continuous timer ticks and have them programmed to occur as required. This option saves power as the system can remain in idle state for longer.
      By default dynamic tick is disabled during the boot, and can be manually enabled with:
      echo 1 > /sys/devices/system/timer/timer0/dyn_tick
      Alternatively, if you want dynamic tick automatically enabled during boot, pass "dyntick=enable" via the kernel command string.
      Please note that dynamic tick may affect the accuracy of timekeeping on some platforms depending on the implementation. Currently at least OMAP, PXA2xx and SA11x0 platforms are known to have accurate timekeeping with dynamic tick.


  • Option: ARCH_DISCONTIGMEM_ENABLE
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default (ARCH_LH7A40X && !LH7A40X_CONTIGMEM)
      Say Y to support efficient handling of discontiguous physical memory, for architectures which are either NUMA (Non-Uniform Memory Access) or have huge holes in the physical address space for other reasons. See <file:Documentation/vm/numa> for more.



  • Option: LEDS
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Timer and CPU usage LEDs
    • depends on ARCH_CDB89712 || ARCH_CO285 || ARCH_EBSA110 || \ ARCH_EBSA285 || ARCH_IMX || ARCH_INTEGRATOR || \ ARCH_LUBBOCK || MACH_MAINSTONE || ARCH_NETWINDER || \ ARCH_OMAP || ARCH_P720T || ARCH_PXA_IDP || \ ARCH_SA1100 || ARCH_SHARK || ARCH_VERSATILE
      If you say Y here, the LEDs on your machine will be used to provide useful information about your current system status.
      If you are compiling a kernel for a NetWinder or EBSA-285, you will be able to select which LEDs are active using the options below. If you are compiling a kernel for the EBSA-110 or the LART however, the red LED will simply flash regularly to indicate that the system is still functional. It is safe to say Y here if you have a CATS system, but the driver will do nothing.


  • Option: LEDS_TIMER
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Timer LED if (!ARCH_CDB89712 && !ARCH_OMAP) || \ MACH_OMAP_H2 || MACH_OMAP_PERSEUS2
    • depends on LEDS
    • default y if ARCH_EBSA110
      If you say Y here, one of the system LEDs (the green one on the NetWinder, the amber one on the EBSA285, or the red one on the LART) will flash regularly to indicate that the system is still operational. This is mainly useful to kernel hackers who are debugging unstable kernels.
      The LART uses the same LED for both Timer LED and CPU usage LED functions. You may choose to use both, but the Timer LED function will overrule the CPU usage LED.


  • Option: LEDS_CPU
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) CPU usage LED if (!ARCH_CDB89712 && !ARCH_EBSA110 && \

!ARCH_OMAP) || MACH_OMAP_H2 || MACH_OMAP_PERSEUS2

    • depends on LEDS
      If you say Y here, the red LED will be used to give a good real time indication of CPU usage, by lighting whenever the idle task is not currently executing.
      The LART uses the same LED for both Timer LED and CPU usage LED functions. You may choose to use both, but the Timer LED function will overrule the CPU usage LED.


  • Option: ALIGNMENT_TRAP
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • default y if !ARCH_EBSA110
      ARM processors can not fetch/store information which is not naturally aligned on the bus, i.e., a 4 byte fetch must start at an address divisible by 4. On 32-bit ARM processors, these non-aligned fetch/store instructions will be emulated in software if you say here, which has a severe performance impact. This is necessary for correct operation of some network protocols. With an IP-only configuration it is safe to say N, otherwise say Y.


Boot optionsEdit

Compressed boot loader in ROM. Yes, we really want to ask about
TEXT and BSS so we preserve their values in the config files.


  • Option: ZBOOT_ROM_TEXT
    • Kernel Versions: 2.6.15.6 ...

"Compressed ROM boot loader base address"

    • default "0"
      The physical address at which the ROM-able zImage is to be placed in the target. Platforms which normally make use of ROM-able zImage formats normally set this to a suitable value in their defconfig file.
      If ZBOOT_ROM is not enabled, this has no effect.


  • Option: ZBOOT_ROM_BSS
    • Kernel Versions: 2.6.15.6 ...

"Compressed ROM boot loader BSS address"

    • default "0"
      The base address of 64KiB of read/write memory in the target for the ROM-able zImage, which must be available while the decompressor is running. Platforms which normally make use of ROM-able zImage formats normally set this to a suitable value in their defconfig file.
      If ZBOOT_ROM is not enabled, this has no effect.


  • Option: ZBOOT_ROM
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Compressed boot loader in ROM/flash
    • depends on ZBOOT_ROM_TEXT != ZBOOT_ROM_BSS
      Say Y here if you intend to execute your compressed kernel image (zImage) directly from ROM or flash. If unsure, say N.


  • Option: CMDLINE
    • Kernel Versions: 2.6.15.6 ...

"Default kernel command string"

    • default ""
      On some architectures (EBSA110 and CATS), there is currently no way for the boot loader to pass arguments to the kernel. For these architectures, you should supply some command-line options at build time by entering them here. As a minimum, you should specify the memory size and the root device (e.g., mem=64M root=/dev/nfs).


  • Option: XIP_KERNEL
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Kernel Execute-In-Place from ROM
    • depends on !ZBOOT_ROM
      Execute-In-Place allows the kernel to run from non-volatile storage directly addressable by the CPU, such as NOR flash. This saves RAM space since the text section of the kernel is not loaded from flash to RAM. Read-write sections, such as the data section and stack, are still copied to RAM. The XIP kernel is not compressed since it has to run directly from flash, so it will take more space to store it. The flash address used to link the kernel object files, and for storing it, is configuration dependent. Therefore, if you say Y here, you must know the proper physical address where to store the kernel image depending on your own flash memory usage.
      Also note that the make target becomes "make xipImage" rather than make zImage or make Image. The final kernel binary to put in ROM memory will be arch/arm/boot/xipImage.
      If unsure, say N.


  • Option: XIP_PHYS_ADDR
    • Kernel Versions: 2.6.15.6 ...

"XIP Kernel Physical Location"

    • depends on XIP_KERNEL
    • default "0x00080000"
      This is the physical address in your flash memory the kernel will be linked for and stored to. This address is dependent on your own flash usage.


(ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP1)

CPU Frequency scalingEdit


  • Option: CPU_FREQ_SA1100
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • depends on CPU_FREQ && (SA1100_H3100 || SA1100_H3600 || SA1100_H3800 || SA1100_LART || SA1100_PLEB || SA1100_BADGE4 || SA1100_HACKKIT)
    • default y


  • Option: CPU_FREQ_SA1110
    • Kernel Versions: 2.6.15.6 ...
    • (on/off)
    • depends on CPU_FREQ && (SA1100_ASSABET || SA1100_CERF || SA1100_PT_SYSTEM3)
    • default y


  • Option: CPU_FREQ_INTEGRATOR
    • Kernel Versions: 2.6.15.6 ...
    • (on/off/module) CPUfreq driver for ARM Integrator CPUs
    • depends on ARCH_INTEGRATOR && CPU_FREQ
    • default y
      This enables the CPUfreq driver for ARM Integrator CPUs.
      For details, take a look at <file:Documentation/cpu-freq>.
      If in doubt, say Y.



Floating point emulationEdit

"At least one emulation must be selected"


  • Option: FPE_NWFPE
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) NWFPE math emulation
      Say Y to include the NWFPE floating point emulator in the kernel. This is necessary to run most binaries. Linux does not currently support floating point hardware so you need to say Y here even if your machine has an FPA or floating point co-processor podule.
      You may say N here if you are going to load the Acorn FPEmulator early in the bootup.


  • Option: FPE_NWFPE_XP
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) Support extended precision
    • depends on FPE_NWFPE
      Say Y to include 80-bit support in the kernel floating-point emulator. Otherwise, only 32 and 64-bit support is compiled in. Note that gcc does not generate 80-bit operations by default, so in most cases this option only enlarges the size of the floating point emulator without any good reason.
      You almost surely want to say N here.


  • Option: FPE_FASTFPE
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) FastFPE math emulation (EXPERIMENTAL)
    • depends on !CPU_32v3 && EXPERIMENTAL
      Say Y here to include the FAST floating point emulator in the kernel. This is an experimental much faster emulator which now also has full precision for the mantissa. It does not support any exceptions. It is very simple, and approximately 3-6 times faster than NWFPE.
      It should be sufficient for most programs. It may be not suitable for scientific calculations, but you have to check this for yourself. If you do not feel you need a faster FP emulation you should better choose NWFPE.


  • Option: VFP
    • Kernel Versions: 2.6.15.6 ...
    • (on/off) VFP-format floating point maths
    • depends on CPU_V6 || CPU_ARM926T
      Say Y to include VFP support code in the kernel. This is needed if your hardware includes a VFP unit.
      Please see <file:Documentation/arm/VFP/release-notes.txt> for release notes and additional status information.
      Say N if your target does not have VFP hardware.


Userspace binary formatsEdit


  • Option: ARTHUR
    • Kernel Versions: 2.6.15.6 ...
    • (on/off/module) RISC OS personality
      Say Y here to include the kernel code necessary if you want to run Acorn RISC OS/Arthur binaries under Linux. This code is still very experimental; if this sounds frightening, say N and sleep in peace. You can also say M here to compile this support as a module (which will be called arthur).


Power management optionsEdit


  • Option: APM
    • Kernel Versions: 2.6.15.6 ...
    • (on/off/module) Advanced Power Management Emulation
    • depends on PM_LEGACY
      APM is a BIOS specification for saving power using several different techniques. This is mostly useful for battery powered laptops with APM compliant BIOSes. If you say Y here, the system time will be reset after a RESUME operation, the /proc/apm device will provide battery status information, and user-space programs will receive notification of APM "events" (e.g. battery status change).
      In order to use APM, you will need supporting software. For location and more information, read <file:Documentation/pm.txt> and the Battery Powered Linux mini-HOWTO, available from <http://www.tldp.org/docs.html#howto>.
      This driver does not spin down disk drives (see the hdparm(8) manpage ("man 8 hdparm") for that), and it doesn't turn off VESA-compliant "green" monitors.
      Generally, if you don't have a battery in your machine, there isn't much point in using this driver and you should say N. If you get random kernel OOPSes or reboots that don't seem to be related to anything, try disabling/enabling this option (or disabling/enabling APM in your BIOS).



Device DriversEdit


ALIGNMENT_TRAP







PCMCIA || ARCH_CLPS7500 || ARCH_IOP3XX || ARCH_IXP4XX \ || ARCH_L7200 || ARCH_LH7A40X || ARCH_PXA || ARCH_RPC \ || ARCH_S3C2410 || ARCH_SA1100 || ARCH_SHARK || FOOTBRIDGE










input before char - char/joystick depends on it. As does USB.





source "drivers/l3]]
















Linux Kernel Configuration

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