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Kconfig
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#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.txt.
#
mainmenu "Linux Kernel Configuration"
config X86_32
bool
default y
help
This is Linux's home port. Linux was originally native to the Intel
386, and runs on all the later x86 processors including the Intel
486, 586, Pentiums, and various instruction-set-compatible chips by
AMD, Cyrix, and others.
config GENERIC_TIME
bool
default y
config LOCKDEP_SUPPORT
bool
default y
config STACKTRACE_SUPPORT
bool
default y
config SEMAPHORE_SLEEPERS
bool
default y
config X86
bool
default y
config MMU
bool
default y
config ZONE_DMA
bool
default y
config SBUS
bool
config GENERIC_ISA_DMA
bool
default y
config GENERIC_IOMAP
bool
default y
config GENERIC_BUG
bool
default y
depends on BUG
config GENERIC_HWEIGHT
bool
default y
config ARCH_MAY_HAVE_PC_FDC
bool
default y
config DMI
bool
default y
source "init/Kconfig"
menu "Processor type and features"
config SMP
bool "Symmetric multi-processing support"
---help---
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,
singleprocessor machines. On a singleprocessor machine, the kernel
will run faster if you say N here.
Note that if you say Y here and choose architecture "586" or
"Pentium" under "Processor family", the kernel will not work on 486
architectures. Similarly, multiprocessor kernels for the "PPro"
architecture may not work on all Pentium based boards.
People using multiprocessor machines who say Y here should also say
Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
Management" code will be disabled if you say Y 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.tldp.org/docs.html#howto>.
If you don't know what to do here, say N.
choice
prompt "Subarchitecture Type"
default X86_PC
config X86_PC
bool "PC-compatible"
help
Choose this option if your computer is a standard PC or compatible.
config X86_ELAN
bool "AMD Elan"
help
Select this for an AMD Elan processor.
Do not use this option for K6/Athlon/Opteron processors!
If unsure, choose "PC-compatible" instead.
config X86_VOYAGER
bool "Voyager (NCR)"
help
Voyager is an MCA-based 32-way capable SMP architecture proprietary
to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
*** WARNING ***
If you do not specifically know you have a Voyager based machine,
say N here, otherwise the kernel you build will not be bootable.
config X86_NUMAQ
bool "NUMAQ (IBM/Sequent)"
select SMP
select NUMA
help
This option is used for getting Linux to run on a (IBM/Sequent) NUMA
multiquad box. This changes the way that processors are bootstrapped,
and uses Clustered Logical APIC addressing mode instead of Flat Logical.
You will need a new lynxer.elf file to flash your firmware with - send
email to <[email protected]>.
config X86_SUMMIT
bool "Summit/EXA (IBM x440)"
depends on SMP
help
This option is needed for IBM systems that use the Summit/EXA chipset.
In particular, it is needed for the x440.
If you don't have one of these computers, you should say N here.
If you want to build a NUMA kernel, you must select ACPI.
config X86_BIGSMP
bool "Support for other sub-arch SMP systems with more than 8 CPUs"
depends on SMP
help
This option is needed for the systems that have more than 8 CPUs
and if the system is not of any sub-arch type above.
If you don't have such a system, you should say N here.
config X86_VISWS
bool "SGI 320/540 (Visual Workstation)"
help
The SGI Visual Workstation series is an IA32-based workstation
based on SGI systems chips with some legacy PC hardware attached.
Say Y here to create a kernel to run on the SGI 320 or 540.
A kernel compiled for the Visual Workstation will not run on PCs
and vice versa. See <file:Documentation/sgi-visws.txt> for details.
config X86_GENERICARCH
bool "Generic architecture (Summit, bigsmp, ES7000, default)"
help
This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
It is intended for a generic binary kernel.
If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
config X86_ES7000
bool "Support for Unisys ES7000 IA32 series"
depends on SMP
help
Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
supposed to run on an IA32-based Unisys ES7000 system.
Only choose this option if you have such a system, otherwise you
should say N here.
endchoice
config PARAVIRT
bool "Paravirtualization support (EXPERIMENTAL)"
depends on EXPERIMENTAL
depends on !(X86_VISWS || X86_VOYAGER)
help
Paravirtualization is a way of running multiple instances of
Linux on the same machine, under a hypervisor. This option
changes the kernel so it can modify itself when it is run
under a hypervisor, improving performance significantly.
However, when run without a hypervisor the kernel is
theoretically slower. If in doubt, say N.
config ACPI_SRAT
bool
default y
depends on ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
select ACPI_NUMA
config HAVE_ARCH_PARSE_SRAT
bool
default y
depends on ACPI_SRAT
config X86_SUMMIT_NUMA
bool
default y
depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
config X86_CYCLONE_TIMER
bool
default y
depends on X86_SUMMIT || X86_GENERICARCH
config ES7000_CLUSTERED_APIC
bool
default y
depends on SMP && X86_ES7000 && MPENTIUMIII
source "arch/i386/Kconfig.cpu"
config HPET_TIMER
bool "HPET Timer Support"
help
This enables the use of the HPET for the kernel's internal timer.
HPET is the next generation timer replacing legacy 8254s.
You can safely choose Y here. However, HPET will only be
activated if the platform and the BIOS support this feature.
Otherwise the 8254 will be used for timing services.
Choose N to continue using the legacy 8254 timer.
config HPET_EMULATE_RTC
bool
depends on HPET_TIMER && RTC=y
default y
config NR_CPUS
int "Maximum number of CPUs (2-255)"
range 2 255
depends on SMP
default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
default "8"
help
This allows you to specify the maximum number of CPUs which this
kernel will support. The maximum supported value is 255 and the
minimum value which makes sense is 2.
This is purely to save memory - each supported CPU adds
approximately eight kilobytes to the kernel image.
config SCHED_SMT
bool "SMT (Hyperthreading) scheduler support"
depends on X86_HT
help
SMT scheduler support improves the CPU scheduler's decision making
when dealing with Intel Pentium 4 chips with HyperThreading at a
cost of slightly increased overhead in some places. If unsure say
N here.
config SCHED_MC
bool "Multi-core scheduler support"
depends on X86_HT
default y
help
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
increased overhead in some places. If unsure say N here.
source "kernel/Kconfig.preempt"
config X86_UP_APIC
bool "Local APIC support on uniprocessors"
depends on !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
help
A local APIC (Advanced Programmable Interrupt Controller) is an
integrated interrupt controller in the CPU. If you have a single-CPU
system which has a processor with a local APIC, you can say Y here to
enable and use it. If you say Y here even though your machine doesn't
have a local APIC, then the kernel will still run with no slowdown at
all. The local APIC supports CPU-generated self-interrupts (timer,
performance counters), and the NMI watchdog which detects hard
lockups.
config X86_UP_IOAPIC
bool "IO-APIC support on uniprocessors"
depends on X86_UP_APIC
help
An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
SMP-capable replacement for PC-style interrupt controllers. Most
SMP systems and many recent uniprocessor systems have one.
If you have a single-CPU system with an IO-APIC, you can say Y here
to use it. If you say Y here even though your machine doesn't have
an IO-APIC, then the kernel will still run with no slowdown at all.
config X86_LOCAL_APIC
bool
depends on X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH
default y
config X86_IO_APIC
bool
depends on X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH
default y
config X86_VISWS_APIC
bool
depends on X86_VISWS
default y
config X86_MCE
bool "Machine Check Exception"
depends on !X86_VOYAGER
---help---
Machine Check Exception support allows the processor to notify the
kernel if it detects a problem (e.g. overheating, component failure).
The action the kernel takes depends on the severity of the problem,
ranging from a warning message on the console, to halting the machine.
Your processor must be a Pentium or newer to support this - check the
flags in /proc/cpuinfo for mce. Note that some older Pentium systems
have a design flaw which leads to false MCE events - hence MCE is
disabled on all P5 processors, unless explicitly enabled with "mce"
as a boot argument. Similarly, if MCE is built in and creates a
problem on some new non-standard machine, you can boot with "nomce"
to disable it. MCE support simply ignores non-MCE processors like
the 386 and 486, so nearly everyone can say Y here.
config X86_MCE_NONFATAL
tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
depends on X86_MCE
help
Enabling this feature starts a timer that triggers every 5 seconds which
will look at the machine check registers to see if anything happened.
Non-fatal problems automatically get corrected (but still logged).
Disable this if you don't want to see these messages.
Seeing the messages this option prints out may be indicative of dying hardware,
or out-of-spec (ie, overclocked) hardware.
This option only does something on certain CPUs.
(AMD Athlon/Duron and Intel Pentium 4)
config X86_MCE_P4THERMAL
bool "check for P4 thermal throttling interrupt."
depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
help
Enabling this feature will cause a message to be printed when the P4
enters thermal throttling.
config VM86
default y
bool "Enable VM86 support" if EMBEDDED
help
This option is required by programs like DOSEMU to run 16-bit legacy
code on X86 processors. It also may be needed by software like
XFree86 to initialize some video cards via BIOS. Disabling this
option saves about 6k.
config TOSHIBA
tristate "Toshiba Laptop support"
---help---
This adds a driver to safely access the System Management Mode of
the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
not work on models with a Phoenix BIOS. The System Management Mode
is used to set the BIOS and power saving options on Toshiba portables.
For information on utilities to make use of this driver see the
Toshiba Linux utilities web site at:
<http://www.buzzard.org.uk/toshiba/>.
Say Y if you intend to run this kernel on a Toshiba portable.
Say N otherwise.
config I8K
tristate "Dell laptop support"
---help---
This adds a driver to safely access the System Management Mode
of the CPU on the Dell Inspiron 8000. The System Management Mode
is used to read cpu temperature and cooling fan status and to
control the fans on the I8K portables.
This driver has been tested only on the Inspiron 8000 but it may
also work with other Dell laptops. You can force loading on other
models by passing the parameter `force=1' to the module. Use at
your own risk.
For information on utilities to make use of this driver see the
I8K Linux utilities web site at:
<http://people.debian.org/~dz/i8k/>
Say Y if you intend to run this kernel on a Dell Inspiron 8000.
Say N otherwise.
config X86_REBOOTFIXUPS
bool "Enable X86 board specific fixups for reboot"
depends on X86
default n
---help---
This enables chipset and/or board specific fixups to be done
in order to get reboot to work correctly. This is only needed on
some combinations of hardware and BIOS. The symptom, for which
this config is intended, is when reboot ends with a stalled/hung
system.
Currently, the only fixup is for the Geode GX1/CS5530A/TROM2.1.
combination.
Say Y if you want to enable the fixup. Currently, it's safe to
enable this option even if you don't need it.
Say N otherwise.
config MICROCODE
tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
select FW_LOADER
---help---
If you say Y here and also to "/dev file system support" in the
'File systems' section, you will be able to update the microcode on
Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
Pentium III, Pentium 4, Xeon etc. You will obviously need the
actual microcode binary data itself which is not shipped with the
Linux kernel.
For latest news and information on obtaining all the required
ingredients for this driver, check:
<http://www.urbanmyth.org/microcode/>.
To compile this driver as a module, choose M here: the
module will be called microcode.
config MICROCODE_OLD_INTERFACE
bool
depends on MICROCODE
default y
config X86_MSR
tristate "/dev/cpu/*/msr - Model-specific register support"
help
This device gives privileged processes access to the x86
Model-Specific Registers (MSRs). It is a character device with
major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
MSR accesses are directed to a specific CPU on multi-processor
systems.
config X86_CPUID
tristate "/dev/cpu/*/cpuid - CPU information support"
help
This device gives processes access to the x86 CPUID instruction to
be executed on a specific processor. It is a character device
with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
/dev/cpu/31/cpuid.
source "drivers/firmware/Kconfig"
choice
prompt "High Memory Support"
default HIGHMEM4G if !X86_NUMAQ
default HIGHMEM64G if X86_NUMAQ
config NOHIGHMEM
bool "off"
depends on !X86_NUMAQ
---help---
Linux can use up to 64 Gigabytes of physical memory on x86 systems.
However, the address space of 32-bit x86 processors is only 4
Gigabytes large. That means that, if you have a large amount of
physical memory, not all of it can be "permanently mapped" by the
kernel. The physical memory that's not permanently mapped is called
"high memory".
If you are compiling a kernel which will never run on a machine with
more than 1 Gigabyte total physical RAM, answer "off" here (default
choice and suitable for most users). This will result in a "3GB/1GB"
split: 3GB are mapped so that each process sees a 3GB virtual memory
space and the remaining part of the 4GB virtual memory space is used
by the kernel to permanently map as much physical memory as
possible.
If the machine has between 1 and 4 Gigabytes physical RAM, then
answer "4GB" here.
If more than 4 Gigabytes is used then answer "64GB" here. This
selection turns Intel PAE (Physical Address Extension) mode on.
PAE implements 3-level paging on IA32 processors. PAE is fully
supported by Linux, PAE mode is implemented on all recent Intel
processors (Pentium Pro and better). NOTE: If you say "64GB" here,
then the kernel will not boot on CPUs that don't support PAE!
The actual amount of total physical memory will either be
auto detected or can be forced by using a kernel command line option
such as "mem=256M". (Try "man bootparam" or see the documentation of
your boot loader (lilo or loadlin) about how to pass options to the
kernel at boot time.)
If unsure, say "off".
config HIGHMEM4G
bool "4GB"
depends on !X86_NUMAQ
help
Select this if you have a 32-bit processor and between 1 and 4
gigabytes of physical RAM.
config HIGHMEM64G
bool "64GB"
depends on X86_CMPXCHG64
help
Select this if you have a 32-bit processor and more than 4
gigabytes of physical RAM.
endchoice
choice
depends on EXPERIMENTAL
prompt "Memory split" if EMBEDDED
default VMSPLIT_3G
help
Select the desired split between kernel and user memory.
If the address range available to the kernel is less than the
physical memory installed, the remaining memory will be available
as "high memory". Accessing high memory is a little more costly
than low memory, as it needs to be mapped into the kernel first.
Note that increasing the kernel address space limits the range
available to user programs, making the address space there
tighter. Selecting anything other than the default 3G/1G split
will also likely make your kernel incompatible with binary-only
kernel modules.
If you are not absolutely sure what you are doing, leave this
option alone!
config VMSPLIT_3G
bool "3G/1G user/kernel split"
config VMSPLIT_3G_OPT
depends on !HIGHMEM
bool "3G/1G user/kernel split (for full 1G low memory)"
config VMSPLIT_2G
bool "2G/2G user/kernel split"
config VMSPLIT_1G
bool "1G/3G user/kernel split"
endchoice
config PAGE_OFFSET
hex
default 0xB0000000 if VMSPLIT_3G_OPT
default 0x78000000 if VMSPLIT_2G
default 0x40000000 if VMSPLIT_1G
default 0xC0000000
config HIGHMEM
bool
depends on HIGHMEM64G || HIGHMEM4G
default y
config X86_PAE
bool
depends on HIGHMEM64G
default y
select RESOURCES_64BIT
# Common NUMA Features
config NUMA
bool "Numa Memory Allocation and Scheduler Support"
depends on SMP && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI)
default n if X86_PC
default y if (X86_NUMAQ || X86_SUMMIT)
comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
config NODES_SHIFT
int
default "4" if X86_NUMAQ
default "3"
depends on NEED_MULTIPLE_NODES
config HAVE_ARCH_BOOTMEM_NODE
bool
depends on NUMA
default y
config ARCH_HAVE_MEMORY_PRESENT
bool
depends on DISCONTIGMEM
default y
config NEED_NODE_MEMMAP_SIZE
bool
depends on DISCONTIGMEM || SPARSEMEM
default y
config HAVE_ARCH_ALLOC_REMAP
bool
depends on NUMA
default y
config ARCH_FLATMEM_ENABLE
def_bool y
depends on (ARCH_SELECT_MEMORY_MODEL && X86_PC)
config ARCH_DISCONTIGMEM_ENABLE
def_bool y
depends on NUMA
config ARCH_DISCONTIGMEM_DEFAULT
def_bool y
depends on NUMA
config ARCH_SPARSEMEM_ENABLE
def_bool y
depends on (NUMA || (X86_PC && EXPERIMENTAL))
select SPARSEMEM_STATIC
config ARCH_SELECT_MEMORY_MODEL
def_bool y
depends on ARCH_SPARSEMEM_ENABLE
config ARCH_POPULATES_NODE_MAP
def_bool y
source "mm/Kconfig"
config HIGHPTE
bool "Allocate 3rd-level pagetables from highmem"
depends on HIGHMEM4G || HIGHMEM64G
help
The VM uses one page table entry for each page of physical memory.
For systems with a lot of RAM, this can be wasteful of precious
low memory. Setting this option will put user-space page table
entries in high memory.
config MATH_EMULATION
bool "Math emulation"
---help---
Linux can emulate a math coprocessor (used for floating point
operations) if you don't have one. 486DX and Pentium processors have
a math coprocessor built in, 486SX and 386 do not, unless you added
a 487DX or 387, respectively. (The messages during boot time can
give you some hints here ["man dmesg"].) Everyone needs either a
coprocessor or this emulation.
If you don't have a math coprocessor, you need to say Y here; if you
say Y here even though you have a coprocessor, the coprocessor will
be used nevertheless. (This behavior can be changed with the kernel
command line option "no387", which comes handy if your coprocessor
is broken. Try "man bootparam" or see the documentation of your boot
loader (lilo or loadlin) about how to pass options to the kernel at
boot time.) This means that it is a good idea to say Y here if you
intend to use this kernel on different machines.
More information about the internals of the Linux math coprocessor
emulation can be found in <file:arch/i386/math-emu/README>.
If you are not sure, say Y; apart from resulting in a 66 KB bigger
kernel, it won't hurt.
config MTRR
bool "MTRR (Memory Type Range Register) support"
---help---
On Intel P6 family processors (Pentium Pro, Pentium II and later)
the Memory Type Range Registers (MTRRs) may be used to control
processor access to memory ranges. This is most useful if you have
a video (VGA) card on a PCI or AGP bus. Enabling write-combining
allows bus write transfers to be combined into a larger transfer
before bursting over the PCI/AGP bus. This can increase performance
of image write operations 2.5 times or more. Saying Y here creates a
/proc/mtrr file which may be used to manipulate your processor's
MTRRs. Typically the X server should use this.
This code has a reasonably generic interface so that similar
control registers on other processors can be easily supported
as well:
The Cyrix 6x86, 6x86MX and M II processors have Address Range
Registers (ARRs) which provide a similar functionality to MTRRs. For
these, the ARRs are used to emulate the MTRRs.
The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
write-combining. All of these processors are supported by this code
and it makes sense to say Y here if you have one of them.
Saying Y here also fixes a problem with buggy SMP BIOSes which only
set the MTRRs for the boot CPU and not for the secondary CPUs. This
can lead to all sorts of problems, so it's good to say Y here.
You can safely say Y even if your machine doesn't have MTRRs, you'll
just add about 9 KB to your kernel.
See <file:Documentation/mtrr.txt> for more information.
config EFI
bool "Boot from EFI support"
depends on ACPI
default n
---help---
This enables the kernel to boot on EFI platforms using
system configuration information passed to it from the firmware.
This also enables the kernel to use any EFI runtime services that are
available (such as the EFI variable services).
This option is only useful on systems that have EFI firmware
and will result in a kernel image that is ~8k larger. In addition,
you must use the latest ELILO loader available at
<http://elilo.sourceforge.net> in order to take advantage of
kernel initialization using EFI information (neither GRUB nor LILO know
anything about EFI). However, even with this option, the resultant
kernel should continue to boot on existing non-EFI platforms.
config IRQBALANCE
bool "Enable kernel irq balancing"
depends on SMP && X86_IO_APIC
default y
help
The default yes will allow the kernel to do irq load balancing.
Saying no will keep the kernel from doing irq load balancing.
# turning this on wastes a bunch of space.
# Summit needs it only when NUMA is on
config BOOT_IOREMAP
bool
depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
default y
config SECCOMP
bool "Enable seccomp to safely compute untrusted bytecode"
depends on PROC_FS
default y
help
This kernel feature is useful for number crunching applications
that may need to compute untrusted bytecode during their
execution. By using pipes or other transports made available to
the process as file descriptors supporting the read/write
syscalls, it's possible to isolate those applications in
their own address space using seccomp. Once seccomp is
enabled via /proc/<pid>/seccomp, it cannot be disabled
and the task is only allowed to execute a few safe syscalls
defined by each seccomp mode.
If unsure, say Y. Only embedded should say N here.
source kernel/Kconfig.hz
config KEXEC
bool "kexec system call"
help
kexec is a system call that implements the ability to shutdown your
current kernel, and to start another kernel. It is like a reboot
but it is independent of the system firmware. And like a reboot
you can start any kernel with it, not just Linux.
The name comes from the similarity to the exec system call.
It is an ongoing process to be certain the hardware in a machine
is properly shutdown, so do not be surprised if this code does not
initially work for you. It may help to enable device hotplugging
support. As of this writing the exact hardware interface is
strongly in flux, so no good recommendation can be made.
config CRASH_DUMP
bool "kernel crash dumps (EXPERIMENTAL)"
depends on EXPERIMENTAL
depends on HIGHMEM
help
Generate crash dump after being started by kexec.
This should be normally only set in special crash dump kernels
which are loaded in the main kernel with kexec-tools into
a specially reserved region and then later executed after
a crash by kdump/kexec. The crash dump kernel must be compiled
to a memory address not used by the main kernel or BIOS using
PHYSICAL_START.
For more details see Documentation/kdump/kdump.txt
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
default "0x100000"
help
This gives the physical address where the kernel is loaded.
If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
bzImage will decompress itself to above physical address and
run from there. Otherwise, bzImage will run from the address where
it has been loaded by the boot loader and will ignore above physical
address.
In normal kdump cases one does not have to set/change this option
as now bzImage can be compiled as a completely relocatable image
(CONFIG_RELOCATABLE=y) and be used to load and run from a different
address. This option is mainly useful for the folks who don't want
to use a bzImage for capturing the crash dump and want to use a
vmlinux instead. vmlinux is not relocatable hence a kernel needs
to be specifically compiled to run from a specific memory area
(normally a reserved region) and this option comes handy.
So if you are using bzImage for capturing the crash dump, leave
the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
Otherwise if you plan to use vmlinux for capturing the crash dump
change this value to start of the reserved region (Typically 16MB
0x1000000). In other words, it can be set based on the "X" value as
specified in the "crashkernel=YM@XM" command line boot parameter
passed to the panic-ed kernel. Typically this parameter is set as
crashkernel=64M@16M. Please take a look at
Documentation/kdump/kdump.txt for more details about crash dumps.
Usage of bzImage for capturing the crash dump is recommended as
one does not have to build two kernels. Same kernel can be used
as production kernel and capture kernel. Above option should have
gone away after relocatable bzImage support is introduced. But it
is present because there are users out there who continue to use
vmlinux for dump capture. This option should go away down the
line.
Don't change this unless you know what you are doing.
config RELOCATABLE
bool "Build a relocatable kernel(EXPERIMENTAL)"
depends on EXPERIMENTAL
help
This build a kernel image that retains relocation information
so it can be loaded someplace besides the default 1MB.
The relocations tend to the kernel binary about 10% larger,
but are discarded at runtime.
One use is for the kexec on panic case where the recovery kernel
must live at a different physical address than the primary
kernel.
config PHYSICAL_ALIGN
hex "Alignment value to which kernel should be aligned"
default "0x100000"
range 0x2000 0x400000
help
This value puts the alignment restrictions on physical address
where kernel is loaded and run from. Kernel is compiled for an
address which meets above alignment restriction.
If bootloader loads the kernel at a non-aligned address and
CONFIG_RELOCATABLE is set, kernel will move itself to nearest
address aligned to above value and run from there.
If bootloader loads the kernel at a non-aligned address and
CONFIG_RELOCATABLE is not set, kernel will ignore the run time
load address and decompress itself to the address it has been
compiled for and run from there. The address for which kernel is
compiled already meets above alignment restrictions. Hence the
end result is that kernel runs from a physical address meeting
above alignment restrictions.
Don't change this unless you know what you are doing.
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
---help---
Say Y here to experiment with turning CPUs off and on, and to
enable suspend on SMP systems. CPUs can be controlled through
/sys/devices/system/cpu.
config COMPAT_VDSO
bool "Compat VDSO support"
default y
depends on !PARAVIRT
help
Map the VDSO to the predictable old-style address too.
---help---
Say N here if you are running a sufficiently recent glibc
version (2.3.3 or later), to remove the high-mapped
VDSO mapping and to exclusively use the randomized VDSO.
If unsure, say Y.
endmenu
config ARCH_ENABLE_MEMORY_HOTPLUG
def_bool y
depends on HIGHMEM
menu "Power management options (ACPI, APM)"
depends on !X86_VOYAGER
source kernel/power/Kconfig
source "drivers/acpi/Kconfig"
menu "APM (Advanced Power Management) BIOS Support"
depends on PM && !X86_VISWS
config APM
tristate "APM (Advanced Power Management) BIOS support"
depends on PM
---help---
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).
If you select "Y" here, you can disable actual use of the APM
BIOS by passing the "apm=off" option to the kernel at boot time.
Note that the APM support is almost completely disabled for
machines with more than one CPU.
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.
This driver does not support the TI 4000M TravelMate and the ACER
486/DX4/75 because they don't have compliant BIOSes. Many "green"
desktop machines also don't have compliant BIOSes, and this driver
may cause those machines to panic during the boot phase.
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).
Some other things you should try when experiencing seemingly random,
"weird" problems:
1) make sure that you have enough swap space and that it is
enabled.
2) pass the "no-hlt" option to the kernel
3) switch on floating point emulation in the kernel and pass
the "no387" option to the kernel
4) pass the "floppy=nodma" option to the kernel
5) pass the "mem=4M" option to the kernel (thereby disabling
all but the first 4 MB of RAM)
6) make sure that the CPU is not over clocked.
7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
8) disable the cache from your BIOS settings
9) install a fan for the video card or exchange video RAM
10) install a better fan for the CPU
11) exchange RAM chips
12) exchange the motherboard.
To compile this driver as a module, choose M here: the
module will be called apm.
config APM_IGNORE_USER_SUSPEND
bool "Ignore USER SUSPEND"
depends on APM
help
This option will ignore USER SUSPEND requests. On machines with a
compliant APM BIOS, you want to say N. However, on the NEC Versa M
series notebooks, it is necessary to say Y because of a BIOS bug.
config APM_DO_ENABLE
bool "Enable PM at boot time"
depends on APM
---help---
Enable APM features at boot time. From page 36 of the APM BIOS
specification: "When disabled, the APM BIOS does not automatically
power manage devices, enter the Standby State, enter the Suspend
State, or take power saving steps in response to CPU Idle calls."
This driver will make CPU Idle calls when Linux is idle (unless this
feature is turned off -- see "Do CPU IDLE calls", below). This
should always save battery power, but more complicated APM features
will be dependent on your BIOS implementation. You may need to turn
this option off if your computer hangs at boot time when using APM
support, or if it beeps continuously instead of suspending. Turn
this off if you have a NEC UltraLite Versa 33/C or a Toshiba
T400CDT. This is off by default since most machines do fine without
this feature.
config APM_CPU_IDLE
bool "Make CPU Idle calls when idle"
depends on APM
help
Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
On some machines, this can activate improved power savings, such as
a slowed CPU clock rate, when the machine is idle. These idle calls
are made after the idle loop has run for some length of time (e.g.,
333 mS). On some machines, this will cause a hang at boot time or
whenever the CPU becomes idle. (On machines with more than one CPU,
this option does nothing.)
config APM_DISPLAY_BLANK
bool "Enable console blanking using APM"
depends on APM
help
Enable console blanking using the APM. Some laptops can use this to
turn off the LCD backlight when the screen blanker of the Linux