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bdc807871d
kernel_optimize_test/arch/m32r/Kconfig
H. Peter Anvin bdc807871d 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 09:22:39 -08:00

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#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.txt.
#
mainmenu "Linux/M32R Kernel Configuration"
config M32R
bool
default y
select HAVE_OPROFILE
config SBUS
bool
config GENERIC_ISA_DMA
bool
default y
config ZONE_DMA
bool
default y
config GENERIC_HARDIRQS
bool
default y
config GENERIC_IRQ_PROBE
bool
default y
config NO_IOPORT
def_bool y
config NO_DMA
def_bool y
config ARCH_SUPPORTS_AOUT
def_bool y
config HZ
int
default 100
source "init/Kconfig"
menu "Processor type and features"
choice
prompt "Platform Type"
default PLAT_MAPPI
config PLAT_MAPPI
bool "Mappi-I"
help
The Mappi-I is an FPGA board for SOC (System-On-a-Chip) prototyping.
You can operate a Linux system on this board by using an M32R
softmacro core, which is a fully-synthesizable functional model
described in Verilog-HDL.
The Mappi-I board was the first platform, which had been used
to port and develop a Linux system for the M32R processor.
Currently, the Mappi-II, an heir to the Mappi-I, is available.
config PLAT_USRV
bool "uServer"
select PLAT_HAS_INT1ICU
config PLAT_M32700UT
bool "M32700UT"
select PLAT_HAS_INT0ICU
select PLAT_HAS_INT1ICU
select PLAT_HAS_INT2ICU
help
The M3T-M32700UT is an evaluation board based on uT-Engine
specification. This board has an M32700 (Chaos) evaluation chip.
You can say Y for SMP, because the M32700 is a single chip
multiprocessor.
config PLAT_OPSPUT
bool "OPSPUT"
select PLAT_HAS_INT0ICU
select PLAT_HAS_INT1ICU
select PLAT_HAS_INT2ICU
help
The OPSPUT is an evaluation board based on uT-Engine
specification. This board has a OPSP-REP chip.
config PLAT_OAKS32R
bool "OAKS32R"
help
The OAKS32R is a tiny, inexpensive evaluation board.
Please note that if you say Y here and choose chip "M32102",
say N for MMU and select a no-MMU version kernel, otherwise
a kernel with MMU support will not work, because the M32102
is a microcontroller for embedded systems and it has no MMU.
config PLAT_MAPPI2
bool "Mappi-II(M3A-ZA36/M3A-ZA52)"
config PLAT_MAPPI3
bool "Mappi-III(M3A-2170)"
config PLAT_M32104UT
bool "M32104UT"
select PLAT_HAS_INT1ICU
help
The M3T-M32104UT is an reference board based on uT-Engine
specification. This board has a M32104 chip.
endchoice
choice
prompt "Processor family"
default CHIP_M32700
config CHIP_M32700
bool "M32700 (Chaos)"
config CHIP_M32102
bool "M32102"
config CHIP_M32104
bool "M32104"
depends on PLAT_M32104UT
config CHIP_VDEC2
bool "VDEC2"
config CHIP_OPSP
bool "OPSP"
endchoice
config MMU
bool "Support for memory management hardware"
depends on CHIP_M32700 || CHIP_VDEC2 || CHIP_OPSP
default y
config TLB_ENTRIES
int "TLB Entries"
depends on CHIP_M32700 || CHIP_VDEC2 || CHIP_OPSP
default 32 if CHIP_M32700 || CHIP_OPSP
default 16 if CHIP_VDEC2
config ISA_M32R
bool
depends on CHIP_M32102 || CHIP_M32104
default y
config ISA_M32R2
bool
depends on CHIP_M32700 || CHIP_VDEC2 || CHIP_OPSP
default y
config ISA_DSP_LEVEL2
bool
depends on CHIP_M32700 || CHIP_OPSP
default y
config ISA_DUAL_ISSUE
bool
depends on CHIP_M32700 || CHIP_OPSP
default y
config PLAT_HAS_INT0ICU
bool
default n
config PLAT_HAS_INT1ICU
bool
default n
config PLAT_HAS_INT2ICU
bool
default n
config BUS_CLOCK
int "Bus Clock [Hz] (integer)"
default "70000000" if PLAT_MAPPI
default "25000000" if PLAT_USRV
default "50000000" if PLAT_MAPPI3
default "50000000" if PLAT_M32700UT
default "50000000" if PLAT_OPSPUT
default "54000000" if PLAT_M32104UT
default "33333333" if PLAT_OAKS32R
default "20000000" if PLAT_MAPPI2
config TIMER_DIVIDE
int "Timer divider (integer)"
default "128"
config CPU_LITTLE_ENDIAN
bool "Generate little endian code"
default n
config MEMORY_START
hex "Physical memory start address (hex)"
default "08000000" if PLAT_MAPPI || PLAT_MAPPI2 || PLAT_MAPPI3
default "08000000" if PLAT_USRV
default "08000000" if PLAT_M32700UT
default "08000000" if PLAT_OPSPUT
default "04000000" if PLAT_M32104UT
default "01000000" if PLAT_OAKS32R
config MEMORY_SIZE
hex "Physical memory size (hex)"
default "08000000" if PLAT_MAPPI3
default "04000000" if PLAT_MAPPI || PLAT_MAPPI2
default "02000000" if PLAT_USRV
default "01000000" if PLAT_M32700UT
default "01000000" if PLAT_OPSPUT
default "01000000" if PLAT_M32104UT
default "00800000" if PLAT_OAKS32R
config NOHIGHMEM
bool
default y
config ARCH_DISCONTIGMEM_ENABLE
bool "Internal RAM Support"
depends on CHIP_M32700 || CHIP_M32102 || CHIP_VDEC2 || CHIP_OPSP || CHIP_M32104
default y
source "mm/Kconfig"
config IRAM_START
hex "Internal memory start address (hex)"
default "00f00000" if !CHIP_M32104
default "00700000" if CHIP_M32104
depends on (CHIP_M32700 || CHIP_M32102 || CHIP_VDEC2 || CHIP_OPSP || CHIP_M32104) && DISCONTIGMEM
config IRAM_SIZE
hex "Internal memory size (hex)"
depends on (CHIP_M32700 || CHIP_M32102 || CHIP_VDEC2 || CHIP_OPSP || CHIP_M32104) && DISCONTIGMEM
default "00080000" if CHIP_M32700
default "00010000" if CHIP_M32102 || CHIP_OPSP || CHIP_M32104
default "00008000" if CHIP_VDEC2
#
# Define implied options from the CPU selection here
#
config GENERIC_LOCKBREAK
bool
default y
depends on SMP && PREEMPT
config RWSEM_GENERIC_SPINLOCK
bool
depends on M32R
default y
config RWSEM_XCHGADD_ALGORITHM
bool
default n
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 SCHED_NO_NO_OMIT_FRAME_POINTER
bool
default y
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.
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.
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 SMP-HOWTO available at
<http://www.linuxdoc.org/docs.html#howto>.
If you don't know what to do here, say N.
config CHIP_M32700_TS1
bool "Workaround code for the M32700 TS1 chip's bug"
depends on (CHIP_M32700 && SMP)
default n
config NR_CPUS
int "Maximum number of CPUs (2-32)"
range 2 32
depends on SMP
default "2"
help
This allows you to specify the maximum number of CPUs which this
kernel will support. The maximum supported value is 32 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.
# Common NUMA Features
config NUMA
bool "Numa Memory Allocation Support"
depends on SMP && BROKEN
default n
config NODES_SHIFT
int
default "1"
depends on NEED_MULTIPLE_NODES
# turning this on wastes a bunch of space.
# Summit needs it only when NUMA is on
config BOOT_IOREMAP
bool
depends on NUMA
default n
endmenu
menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
config PCI
bool "PCI support"
depends on BROKEN
default n
help
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.
choice
prompt "PCI access mode"
depends on PCI
default PCI_GOANY
config PCI_GOBIOS
bool "BIOS"
---help---
On PCI systems, the BIOS can be used to detect the PCI devices and
determine their configuration. However, some old PCI motherboards
have BIOS bugs and may crash if this is done. Also, some embedded
PCI-based systems don't have any BIOS at all. Linux can also try to
detect the PCI hardware directly without using the BIOS.
With this option, you can specify how Linux should detect the PCI
devices. If you choose "BIOS", the BIOS will be used, if you choose
"Direct", the BIOS won't be used, and if you choose "Any", the
kernel will try the direct access method and falls back to the BIOS
if that doesn't work. If unsure, go with the default, which is
"Any".
config PCI_GODIRECT
bool "Direct"
config PCI_GOANY
bool "Any"
endchoice
config PCI_BIOS
bool
depends on PCI && (PCI_GOBIOS || PCI_GOANY)
default y
config PCI_DIRECT
bool
depends on PCI && (PCI_GODIRECT || PCI_GOANY)
default y
source "drivers/pci/Kconfig"
config ISA
bool "ISA support"
help
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. If you have ISA, say Y, otherwise N.
source "drivers/pcmcia/Kconfig"
source "drivers/pci/hotplug/Kconfig"
endmenu
menu "Executable file formats"
source "fs/Kconfig.binfmt"
endmenu
source "net/Kconfig"
source "drivers/Kconfig"
source "fs/Kconfig"
source "arch/m32r/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
source "lib/Kconfig"
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