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302 lines
9.0 KiB
302 lines
9.0 KiB
menu "Kernel hacking"
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config TRACE_IRQFLAGS_SUPPORT
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def_bool y
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source "lib/Kconfig.debug"
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config STRICT_DEVMEM
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bool "Filter access to /dev/mem"
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help
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If this option is disabled, you allow userspace (root) access to all
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of memory, including kernel and userspace memory. Accidental
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access to this is obviously disastrous, but specific access can
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be used by people debugging the kernel. Note that with PAT support
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enabled, even in this case there are restrictions on /dev/mem
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use due to the cache aliasing requirements.
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If this option is switched on, the /dev/mem file only allows
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userspace access to PCI space and the BIOS code and data regions.
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This is sufficient for dosemu and X and all common users of
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/dev/mem.
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If in doubt, say Y.
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config X86_VERBOSE_BOOTUP
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bool "Enable verbose x86 bootup info messages"
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default y
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help
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Enables the informational output from the decompression stage
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(e.g. bzImage) of the boot. If you disable this you will still
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see errors. Disable this if you want silent bootup.
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config EARLY_PRINTK
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bool "Early printk" if EMBEDDED
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default y
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help
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Write kernel log output directly into the VGA buffer or to a serial
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port.
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This is useful for kernel debugging when your machine crashes very
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early before the console code is initialized. For normal operation
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it is not recommended because it looks ugly and doesn't cooperate
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with klogd/syslogd or the X server. You should normally N here,
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unless you want to debug such a crash.
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config EARLY_PRINTK_DBGP
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bool "Early printk via EHCI debug port"
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default n
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depends on EARLY_PRINTK && PCI
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help
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Write kernel log output directly into the EHCI debug port.
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This is useful for kernel debugging when your machine crashes very
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early before the console code is initialized. For normal operation
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it is not recommended because it looks ugly and doesn't cooperate
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with klogd/syslogd or the X server. You should normally N here,
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unless you want to debug such a crash. You need usb debug device.
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config DEBUG_STACKOVERFLOW
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bool "Check for stack overflows"
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depends on DEBUG_KERNEL
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help
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This option will cause messages to be printed if free stack space
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drops below a certain limit.
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config DEBUG_STACK_USAGE
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bool "Stack utilization instrumentation"
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depends on DEBUG_KERNEL
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help
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Enables the display of the minimum amount of free stack which each
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task has ever had available in the sysrq-T and sysrq-P debug output.
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This option will slow down process creation somewhat.
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config DEBUG_PAGEALLOC
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bool "Debug page memory allocations"
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depends on DEBUG_KERNEL
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help
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Unmap pages from the kernel linear mapping after free_pages().
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This results in a large slowdown, but helps to find certain types
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of memory corruptions.
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config DEBUG_PER_CPU_MAPS
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bool "Debug access to per_cpu maps"
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depends on DEBUG_KERNEL
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depends on X86_SMP
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default n
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help
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Say Y to verify that the per_cpu map being accessed has
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been setup. Adds a fair amount of code to kernel memory
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and decreases performance.
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Say N if unsure.
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config X86_PTDUMP
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bool "Export kernel pagetable layout to userspace via debugfs"
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depends on DEBUG_KERNEL
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select DEBUG_FS
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help
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Say Y here if you want to show the kernel pagetable layout in a
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debugfs file. This information is only useful for kernel developers
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who are working in architecture specific areas of the kernel.
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It is probably not a good idea to enable this feature in a production
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kernel.
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If in doubt, say "N"
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config DEBUG_RODATA
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bool "Write protect kernel read-only data structures"
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default y
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depends on DEBUG_KERNEL
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help
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Mark the kernel read-only data as write-protected in the pagetables,
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in order to catch accidental (and incorrect) writes to such const
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data. This is recommended so that we can catch kernel bugs sooner.
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If in doubt, say "Y".
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config DEBUG_RODATA_TEST
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bool "Testcase for the DEBUG_RODATA feature"
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depends on DEBUG_RODATA
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help
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This option enables a testcase for the DEBUG_RODATA
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feature as well as for the change_page_attr() infrastructure.
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If in doubt, say "N"
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config DEBUG_NX_TEST
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tristate "Testcase for the NX non-executable stack feature"
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depends on DEBUG_KERNEL && m
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help
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This option enables a testcase for the CPU NX capability
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and the software setup of this feature.
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If in doubt, say "N"
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config 4KSTACKS
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bool "Use 4Kb for kernel stacks instead of 8Kb"
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depends on X86_32
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help
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If you say Y here the kernel will use a 4Kb stacksize for the
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kernel stack attached to each process/thread. This facilitates
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running more threads on a system and also reduces the pressure
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on the VM subsystem for higher order allocations. This option
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will also use IRQ stacks to compensate for the reduced stackspace.
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config DOUBLEFAULT
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default y
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bool "Enable doublefault exception handler" if EMBEDDED
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depends on X86_32
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help
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This option allows trapping of rare doublefault exceptions that
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would otherwise cause a system to silently reboot. Disabling this
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option saves about 4k and might cause you much additional grey
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hair.
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config IOMMU_DEBUG
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bool "Enable IOMMU debugging"
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depends on GART_IOMMU && DEBUG_KERNEL
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depends on X86_64
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help
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Force the IOMMU to on even when you have less than 4GB of
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memory and add debugging code. On overflow always panic. And
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allow to enable IOMMU leak tracing. Can be disabled at boot
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time with iommu=noforce. This will also enable scatter gather
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list merging. Currently not recommended for production
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code. When you use it make sure you have a big enough
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IOMMU/AGP aperture. Most of the options enabled by this can
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be set more finegrained using the iommu= command line
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options. See Documentation/x86_64/boot-options.txt for more
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details.
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config IOMMU_LEAK
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bool "IOMMU leak tracing"
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depends on DEBUG_KERNEL
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depends on IOMMU_DEBUG
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help
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Add a simple leak tracer to the IOMMU code. This is useful when you
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are debugging a buggy device driver that leaks IOMMU mappings.
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config MMIOTRACE
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bool "Memory mapped IO tracing"
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depends on DEBUG_KERNEL && PCI
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select TRACING
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help
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Mmiotrace traces Memory Mapped I/O access and is meant for
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debugging and reverse engineering. It is called from the ioremap
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implementation and works via page faults. Tracing is disabled by
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default and can be enabled at run-time.
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See Documentation/tracers/mmiotrace.txt.
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If you are not helping to develop drivers, say N.
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config MMIOTRACE_TEST
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tristate "Test module for mmiotrace"
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depends on MMIOTRACE && m
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help
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This is a dumb module for testing mmiotrace. It is very dangerous
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as it will write garbage to IO memory starting at a given address.
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However, it should be safe to use on e.g. unused portion of VRAM.
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Say N, unless you absolutely know what you are doing.
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#
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# IO delay types:
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#
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config IO_DELAY_TYPE_0X80
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int
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default "0"
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config IO_DELAY_TYPE_0XED
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int
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default "1"
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config IO_DELAY_TYPE_UDELAY
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int
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default "2"
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config IO_DELAY_TYPE_NONE
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int
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default "3"
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choice
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prompt "IO delay type"
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default IO_DELAY_0X80
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config IO_DELAY_0X80
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bool "port 0x80 based port-IO delay [recommended]"
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help
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This is the traditional Linux IO delay used for in/out_p.
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It is the most tested hence safest selection here.
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config IO_DELAY_0XED
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bool "port 0xed based port-IO delay"
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help
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Use port 0xed as the IO delay. This frees up port 0x80 which is
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often used as a hardware-debug port.
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config IO_DELAY_UDELAY
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bool "udelay based port-IO delay"
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help
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Use udelay(2) as the IO delay method. This provides the delay
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while not having any side-effect on the IO port space.
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config IO_DELAY_NONE
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bool "no port-IO delay"
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help
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No port-IO delay. Will break on old boxes that require port-IO
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delay for certain operations. Should work on most new machines.
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endchoice
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if IO_DELAY_0X80
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config DEFAULT_IO_DELAY_TYPE
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int
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default IO_DELAY_TYPE_0X80
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endif
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if IO_DELAY_0XED
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config DEFAULT_IO_DELAY_TYPE
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int
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default IO_DELAY_TYPE_0XED
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endif
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if IO_DELAY_UDELAY
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config DEFAULT_IO_DELAY_TYPE
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int
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default IO_DELAY_TYPE_UDELAY
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endif
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if IO_DELAY_NONE
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config DEFAULT_IO_DELAY_TYPE
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int
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default IO_DELAY_TYPE_NONE
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endif
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config DEBUG_BOOT_PARAMS
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bool "Debug boot parameters"
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depends on DEBUG_KERNEL
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depends on DEBUG_FS
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help
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This option will cause struct boot_params to be exported via debugfs.
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config CPA_DEBUG
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bool "CPA self-test code"
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depends on DEBUG_KERNEL
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help
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Do change_page_attr() self-tests every 30 seconds.
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config OPTIMIZE_INLINING
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bool "Allow gcc to uninline functions marked 'inline'"
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help
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This option determines if the kernel forces gcc to inline the functions
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developers have marked 'inline'. Doing so takes away freedom from gcc to
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do what it thinks is best, which is desirable for the gcc 3.x series of
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compilers. The gcc 4.x series have a rewritten inlining algorithm and
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enabling this option will generate a smaller kernel there. Hopefully
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this algorithm is so good that allowing gcc 4.x and above to make the
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decision will become the default in the future. Until then this option
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is there to test gcc for this.
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If unsure, say N.
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endmenu
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