linux/arch/mn10300/Kconfig
Linus Torvalds 8e3e076c5a BKL: revert back to the old spinlock implementation
The generic semaphore rewrite had a huge performance regression on AIM7
(and potentially other BKL-heavy benchmarks) because the generic
semaphores had been rewritten to be simple to understand and fair.  The
latter, in particular, turns a semaphore-based BKL implementation into a
mess of scheduling.

The attempt to fix the performance regression failed miserably (see the
previous commit 00b41ec261 'Revert
"semaphore: fix"'), and so for now the simple and sane approach is to
instead just go back to the old spinlock-based BKL implementation that
never had any issues like this.

This patch also has the advantage of being reported to fix the
regression completely according to Yanmin Zhang, unlike the semaphore
hack which still left a couple percentage point regression.

As a spinlock, the BKL obviously has the potential to be a latency
issue, but it's not really any different from any other spinlock in that
respect.  We do want to get rid of the BKL asap, but that has been the
plan for several years.

These days, the biggest users are in the tty layer (open/release in
particular) and Alan holds out some hope:

  "tty release is probably a few months away from getting cured - I'm
   afraid it will almost certainly be the very last user of the BKL in
   tty to get fixed as it depends on everything else being sanely locked."

so while we're not there yet, we do have a plan of action.

Tested-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Alexander Viro <viro@ftp.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-10 20:58:02 -07:00

374 lines
7.9 KiB
Text

#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.txt.
#
mainmenu "Linux Kernel Configuration"
config MN10300
def_bool y
config AM33
def_bool y
config MMU
def_bool y
config HIGHMEM
def_bool n
config NUMA
def_bool n
config UID16
def_bool y
config RWSEM_GENERIC_SPINLOCK
def_bool y
config RWSEM_XCHGADD_ALGORITHM
bool
config GENERIC_HARDIRQS_NO__DO_IRQ
def_bool y
config GENERIC_CALIBRATE_DELAY
def_bool y
config GENERIC_FIND_NEXT_BIT
def_bool y
config GENERIC_HWEIGHT
def_bool y
config GENERIC_TIME
def_bool y
config GENERIC_BUG
def_bool y
config QUICKLIST
def_bool y
config ARCH_HAS_ILOG2_U32
def_bool y
config ARCH_SUPPORTS_AOUT
def_bool n
# Use the generic interrupt handling code in kernel/irq/
config GENERIC_HARDIRQS
def_bool y
config HOTPLUG_CPU
def_bool n
config HZ
int
default 1000
mainmenu "Matsushita MN10300/AM33 Kernel Configuration"
source "init/Kconfig"
menu "Matsushita MN10300 system setup"
choice
prompt "Unit type"
default MN10300_UNIT_ASB2303
help
This option specifies board for which the kernel will be
compiled. It affects the external peripherals catered for.
config MN10300_UNIT_ASB2303
bool "ASB2303"
config MN10300_UNIT_ASB2305
bool "ASB2305"
endchoice
choice
prompt "Processor support"
default MN10300_PROC_MN103E010
help
This option specifies the processor for which the kernel will be
compiled. It affects the on-chip peripherals catered for.
config MN10300_PROC_MN103E010
bool "MN103E010"
depends on MN10300_UNIT_ASB2303 || MN10300_UNIT_ASB2305
select MN10300_PROC_HAS_TTYSM0
select MN10300_PROC_HAS_TTYSM1
select MN10300_PROC_HAS_TTYSM2
endchoice
choice
prompt "Processor core support"
default MN10300_CPU_AM33V2
help
This option specifies the processor core for which the kernel will be
compiled. It affects the instruction set used.
config MN10300_CPU_AM33V2
bool "AM33v2"
endchoice
config FPU
bool "FPU present"
default y
depends on MN10300_PROC_MN103E010
choice
prompt "CPU Caching mode"
default MN10300_CACHE_WBACK
help
This option determines the caching mode for the kernel.
Write-Back caching mode involves the all reads and writes causing
the affected cacheline to be read into the cache first before being
operated upon. Memory is not then updated by a write until the cache
is filled and a cacheline needs to be displaced from the cache to
make room. Only at that point is it written back.
Write-Through caching only fetches cachelines from memory on a
read. Writes always get written directly to memory. If the affected
cacheline is also in cache, it will be updated too.
The final option is to turn of caching entirely.
config MN10300_CACHE_WBACK
bool "Write-Back"
config MN10300_CACHE_WTHRU
bool "Write-Through"
config MN10300_CACHE_DISABLED
bool "Disabled"
endchoice
menu "Memory layout options"
config KERNEL_RAM_BASE_ADDRESS
hex "Base address of kernel RAM"
default "0x90000000"
config INTERRUPT_VECTOR_BASE
hex "Base address of vector table"
default "0x90000000"
help
The base address of the vector table will be programmed into
the TBR register. It must be on 16MiB address boundary.
config KERNEL_TEXT_ADDRESS
hex "Base address of kernel"
default "0x90001000"
config KERNEL_ZIMAGE_BASE_ADDRESS
hex "Base address of compressed vmlinux image"
default "0x90700000"
endmenu
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 MN10300_CURRENT_IN_E2
bool "Hold current task address in E2 register"
default y
help
This option removes the E2/R2 register from the set available to gcc
for normal use and instead uses it to store the address of the
current process's task_struct whilst in the kernel.
This means the kernel doesn't need to calculate the address each time
"current" is used (take SP, AND with mask and dereference pointer
just to get the address), and instead can just use E2+offset
addressing each time.
This has no effect on userspace.
config MN10300_USING_JTAG
bool "Using JTAG to debug kernel"
default y
help
This options indicates that JTAG will be used to debug the kernel. It
suppresses the use of certain hardware debugging features, such as
single-stepping, which are taken over completely by the JTAG unit.
config MN10300_RTC
bool "Using MN10300 RTC"
depends on MN10300_PROC_MN103E010
default n
help
This option enables support for the RTC, thus enabling time to be
tracked, even when system is powered down. This is available on-chip
on the MN103E010.
config MN10300_WD_TIMER
bool "Using MN10300 watchdog timer"
default y
help
This options indicates that the watchdog timer will be used.
config PCI
bool "Use PCI"
depends on MN10300_UNIT_ASB2305
default y
help
Some systems (such as the ASB2305) have PCI onboard. If you have one
of these boards and you wish to use the PCI facilities, say Y here.
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.
source "drivers/pci/Kconfig"
source "drivers/pcmcia/Kconfig"
menu "MN10300 internal serial options"
config MN10300_PROC_HAS_TTYSM0
bool
default n
config MN10300_PROC_HAS_TTYSM1
bool
default n
config MN10300_PROC_HAS_TTYSM2
bool
default n
config MN10300_TTYSM
bool "Support for ttySM serial ports"
depends on MN10300
default y
select SERIAL_CORE
help
This option enables support for the on-chip serial ports that the
MN10300 has available.
config MN10300_TTYSM_CONSOLE
bool "Support for console on ttySM serial ports"
depends on MN10300_TTYSM
select SERIAL_CORE_CONSOLE
help
This option enables support for a console on the on-chip serial ports
that the MN10300 has available.
#
# /dev/ttySM0
#
config MN10300_TTYSM0
bool "Enable SIF0 (/dev/ttySM0)"
depends on MN10300_TTYSM && MN10300_PROC_HAS_TTYSM0
help
Enable access to SIF0 through /dev/ttySM0 or gdb-stub
choice
prompt "Select the timer to supply the clock for SIF0"
default MN10300_TTYSM0_TIMER8
depends on MN10300_TTYSM0
config MN10300_TTYSM0_TIMER8
bool "Use timer 8 (16-bit)"
config MN10300_TTYSM0_TIMER2
bool "Use timer 2 (8-bit)"
endchoice
#
# /dev/ttySM1
#
config MN10300_TTYSM1
bool "Enable SIF1 (/dev/ttySM1)"
depends on MN10300_TTYSM && MN10300_PROC_HAS_TTYSM1
help
Enable access to SIF1 through /dev/ttySM1 or gdb-stub
choice
prompt "Select the timer to supply the clock for SIF1"
default MN10300_TTYSM0_TIMER9
depends on MN10300_TTYSM1
config MN10300_TTYSM1_TIMER9
bool "Use timer 9 (16-bit)"
config MN10300_TTYSM1_TIMER3
bool "Use timer 3 (8-bit)"
endchoice
#
# /dev/ttySM2
#
config MN10300_TTYSM2
bool "Enable SIF2 (/dev/ttySM2)"
depends on MN10300_TTYSM && MN10300_PROC_HAS_TTYSM2
help
Enable access to SIF2 through /dev/ttySM2 or gdb-stub
choice
prompt "Select the timer to supply the clock for SIF2"
default MN10300_TTYSM0_TIMER10
depends on MN10300_TTYSM2
config MN10300_TTYSM2_TIMER10
bool "Use timer 10 (16-bit)"
endchoice
config MN10300_TTYSM2_CTS
bool "Enable the use of the CTS line /dev/ttySM2"
depends on MN10300_TTYSM2
endmenu
source "mm/Kconfig"
menu "Power management options"
source kernel/power/Kconfig
endmenu
endmenu
menu "Executable formats"
source "fs/Kconfig.binfmt"
endmenu
source "net/Kconfig"
source "drivers/Kconfig"
source "fs/Kconfig"
source "arch/mn10300/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
source "lib/Kconfig"
source "arch/mn10300/oprofile/Kconfig"