kernel_optimize_test/arch/cris/Kconfig

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#
# For a description of the syntax of this configuration file,
# see the Configure script.
#
mainmenu "Linux/CRIS Kernel Configuration"
config MMU
bool
default y
config ZONE_DMA
bool
default y
config NO_DMA
bool
default y
config RWSEM_GENERIC_SPINLOCK
bool
default y
config RWSEM_XCHGADD_ALGORITHM
bool
config ARCH_HAS_ILOG2_U32
bool
default n
config ARCH_HAS_ILOG2_U64
bool
default n
config GENERIC_FIND_NEXT_BIT
bool
default y
config GENERIC_HWEIGHT
bool
default y
config GENERIC_CALIBRATE_DELAY
bool
default y
config IRQ_PER_CPU
bool
default y
config NO_IOPORT
def_bool y
config CRIS
bool
default y
avoid overflows in kernel/time.c When the conversion factor between jiffies and milli- or microseconds is not a single multiply or divide, as for the case of HZ == 300, we currently do a multiply followed by a divide. The intervening result, however, is subject to overflows, especially since the fraction is not simplified (for HZ == 300, we multiply by 300 and divide by 1000). This is exposed to the user when passing a large timeout to poll(), for example. This patch replaces the multiply-divide with a reciprocal multiplication on 32-bit platforms. When the input is an unsigned long, there is no portable way to do this on 64-bit platforms there is no portable way to do this since it requires a 128-bit intermediate result (which gcc does support on 64-bit platforms but may generate libgcc calls, e.g. on 64-bit s390), but since the output is a 32-bit integer in the cases affected, just simplify the multiply-divide (*3/10 instead of *300/1000). The reciprocal multiply used can have off-by-one errors in the upper half of the valid output range. This could be avoided at the expense of having to deal with a potential 65-bit intermediate result. Since the intent is to avoid overflow problems and most of the other time conversions are only semiexact, the off-by-one errors were considered an acceptable tradeoff. At Ralf Baechle's suggestion, this version uses a Perl script to compute the necessary constants. We already have dependencies on Perl for kernel compiles. This does, however, require the Perl module Math::BigInt, which is included in the standard Perl distribution starting with version 5.8.0. In order to support older versions of Perl, include a table of canned constants in the script itself, and structure the script so that Math::BigInt isn't required if pulling values from said table. Running the script requires that the HZ value is available from the Makefile. Thus, this patch also adds the Kconfig variable CONFIG_HZ to the architectures which didn't already have it (alpha, cris, frv, h8300, m32r, m68k, m68knommu, sparc, v850, and xtensa.) It does *not* touch the sh or sh64 architectures, since Paul Mundt has dealt with those separately in the sh tree. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Ralf Baechle <ralf@linux-mips.org>, Cc: Sam Ravnborg <sam@ravnborg.org>, Cc: Paul Mundt <lethal@linux-sh.org>, Cc: Richard Henderson <rth@twiddle.net>, Cc: Michael Starvik <starvik@axis.com>, Cc: David Howells <dhowells@redhat.com>, Cc: Yoshinori Sato <ysato@users.sourceforge.jp>, Cc: Hirokazu Takata <takata@linux-m32r.org>, Cc: Geert Uytterhoeven <geert@linux-m68k.org>, Cc: Roman Zippel <zippel@linux-m68k.org>, Cc: William L. Irwin <sparclinux@vger.kernel.org>, Cc: Chris Zankel <chris@zankel.net>, Cc: H. Peter Anvin <hpa@zytor.com>, Cc: Jan Engelhardt <jengelh@computergmbh.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 20:21:26 +08:00
config HZ
int
default 100
source "init/Kconfig"
menu "General setup"
source "fs/Kconfig.binfmt"
config GENERIC_HARDIRQS
bool
default y
config ETRAX_CMDLINE
string "Kernel command line"
default "root=/dev/mtdblock3"
help
Pass additional commands to the kernel.
config ETRAX_WATCHDOG
bool "Enable ETRAX watchdog"
help
Enable the built-in watchdog timer support on ETRAX based embedded
network computers.
config ETRAX_WATCHDOG_NICE_DOGGY
bool "Disable watchdog during Oops printouts"
depends on ETRAX_WATCHDOG
help
By enabling this you make sure that the watchdog does not bite while
printing oopses. Recommended for development systems but not for
production releases.
config ETRAX_FAST_TIMER
bool "Enable ETRAX fast timer API"
help
This options enables the API to a fast timer implementation using
timer1 to get sub jiffie resolution timers (primarily one-shot
timers).
This is needed if CONFIG_ETRAX_SERIAL_FAST_TIMER is enabled.
config PREEMPT
bool "Preemptible Kernel"
help
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.
source mm/Kconfig
endmenu
menu "Hardware setup"
choice
prompt "Processor type"
default ETRAX100LX
config ETRAX100LX
bool "ETRAX-100LX-v1"
help
Support version 1 of the ETRAX 100LX.
config ETRAX100LX_V2
bool "ETRAX-100LX-v2"
help
Support version 2 of the ETRAX 100LX.
config SVINTO_SIM
bool "ETRAX-100LX-for-xsim-simulator"
help
Support the xsim ETRAX Simulator.
endchoice
config ETRAX_ARCH_V10
bool
default y if ETRAX100LX || ETRAX100LX_V2
default n if !(ETRAX100LX || ETRAX100LX_V2)
config ETRAX_DRAM_SIZE
int "DRAM size (dec, in MB)"
default "8"
help
Size of DRAM (decimal in MB) typically 2, 8 or 16.
config ETRAX_FLASH_BUSWIDTH
int "Buswidth of flash in bytes"
default "2"
help
Width in bytes of the Flash bus (1, 2 or 4). Is usually 2.
source arch/cris/arch-v10/Kconfig
source arch/cris/arch-v32/Kconfig
endmenu
source "net/Kconfig"
# bring in ETRAX built-in drivers
menu "Drivers for built-in interfaces"
source arch/cris/arch-v10/drivers/Kconfig
source arch/cris/arch-v32/drivers/Kconfig
endmenu
source "drivers/base/Kconfig"
# standard linux drivers
source "drivers/mtd/Kconfig"
source "drivers/parport/Kconfig"
source "drivers/pnp/Kconfig"
source "drivers/block/Kconfig"
source "drivers/md/Kconfig"
source "drivers/ide/Kconfig"
source "drivers/scsi/Kconfig"
source "drivers/ieee1394/Kconfig"
source "drivers/message/i2o/Kconfig"
source "drivers/net/Kconfig"
source "drivers/isdn/Kconfig"
source "drivers/telephony/Kconfig"
source "drivers/i2c/Kconfig"
source "drivers/rtc/Kconfig"
#
# input before char - char/joystick depends on it. As does USB.
#
source "drivers/input/Kconfig"
source "drivers/char/Kconfig"
#source drivers/misc/Config.in
source "drivers/media/Kconfig"
source "fs/Kconfig"
source "sound/Kconfig"
source "drivers/pcmcia/Kconfig"
source "drivers/pci/Kconfig"
source "drivers/usb/Kconfig"
source "arch/cris/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
source "lib/Kconfig"