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+menu "Kernel hacking"
+
+config TRACE_IRQFLAGS_SUPPORT
+ def_bool y
+
+source "lib/Kconfig.debug"
+
+config STRICT_DEVMEM
+ bool "Filter access to /dev/mem"
+ ---help---
+ If this option is disabled, you allow userspace (root) access to all
+ of memory, including kernel and userspace memory. Accidental
+ access to this is obviously disastrous, but specific access can
+ be used by people debugging the kernel. Note that with PAT support
+ enabled, even in this case there are restrictions on /dev/mem
+ use due to the cache aliasing requirements.
+
+ If this option is switched on, the /dev/mem file only allows
+ userspace access to PCI space and the BIOS code and data regions.
+ This is sufficient for dosemu and X and all common users of
+ /dev/mem.
+
+ If in doubt, say Y.
+
+config X86_VERBOSE_BOOTUP
+ bool "Enable verbose x86 bootup info messages"
+ default y
+ ---help---
+ Enables the informational output from the decompression stage
+ (e.g. bzImage) of the boot. If you disable this you will still
+ see errors. Disable this if you want silent bootup.
+
+config EARLY_PRINTK
+ bool "Early printk" if EXPERT
+ default y
+ ---help---
+ Write kernel log output directly into the VGA buffer or to a serial
+ port.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. For normal operation
+ it is not recommended because it looks ugly and doesn't cooperate
+ with klogd/syslogd or the X server. You should normally N here,
+ unless you want to debug such a crash.
+
+config EARLY_PRINTK_DBGP
+ bool "Early printk via EHCI debug port"
+ depends on EARLY_PRINTK && PCI
+ ---help---
+ Write kernel log output directly into the EHCI debug port.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. For normal operation
+ it is not recommended because it looks ugly and doesn't cooperate
+ with klogd/syslogd or the X server. You should normally N here,
+ unless you want to debug such a crash. You need usb debug device.
+
+config EARLY_PRINTK_EFI
+ bool "Early printk via the EFI framebuffer"
+ depends on EFI && EARLY_PRINTK
+ select FONT_SUPPORT
+ ---help---
+ Write kernel log output directly into the EFI framebuffer.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized.
+
+config X86_PTDUMP
+ bool "Export kernel pagetable layout to userspace via debugfs"
+ depends on DEBUG_KERNEL
+ select DEBUG_FS
+ ---help---
+ Say Y here if you want to show the kernel pagetable layout in a
+ debugfs file. This information is only useful for kernel developers
+ who are working in architecture specific areas of the kernel.
+ It is probably not a good idea to enable this feature in a production
+ kernel.
+ If in doubt, say "N"
+
+config EFI_PGT_DUMP
+ bool "Dump the EFI pagetable"
+ depends on EFI && X86_PTDUMP
+ ---help---
+ Enable this if you want to dump the EFI page table before
+ enabling virtual mode. This can be used to debug miscellaneous
+ issues with the mapping of the EFI runtime regions into that
+ table.
+
+config DEBUG_RODATA
+ bool "Write protect kernel read-only data structures"
+ default y
+ depends on DEBUG_KERNEL
+ ---help---
+ Mark the kernel read-only data as write-protected in the pagetables,
+ in order to catch accidental (and incorrect) writes to such const
+ data. This is recommended so that we can catch kernel bugs sooner.
+ If in doubt, say "Y".
+
+config DEBUG_RODATA_TEST
+ bool "Testcase for the DEBUG_RODATA feature"
+ depends on DEBUG_RODATA
+ default y
+ ---help---
+ This option enables a testcase for the DEBUG_RODATA
+ feature as well as for the change_page_attr() infrastructure.
+ If in doubt, say "N"
+
+config DEBUG_SET_MODULE_RONX
+ bool "Set loadable kernel module data as NX and text as RO"
+ depends on MODULES
+ ---help---
+ This option helps catch unintended modifications to loadable
+ kernel module's text and read-only data. It also prevents execution
+ of module data. Such protection may interfere with run-time code
+ patching and dynamic kernel tracing - and they might also protect
+ against certain classes of kernel exploits.
+ If in doubt, say "N".
+
+config DEBUG_NX_TEST
+ tristate "Testcase for the NX non-executable stack feature"
+ depends on DEBUG_KERNEL && m
+ ---help---
+ This option enables a testcase for the CPU NX capability
+ and the software setup of this feature.
+ If in doubt, say "N"
+
+config DOUBLEFAULT
+ default y
+ bool "Enable doublefault exception handler" if EXPERT
+ ---help---
+ This option allows trapping of rare doublefault exceptions that
+ would otherwise cause a system to silently reboot. Disabling this
+ option saves about 4k and might cause you much additional grey
+ hair.
+
+config DEBUG_TLBFLUSH
+ bool "Set upper limit of TLB entries to flush one-by-one"
+ depends on DEBUG_KERNEL
+ ---help---
+
+ X86-only for now.
+
+ This option allows the user to tune the amount of TLB entries the
+ kernel flushes one-by-one instead of doing a full TLB flush. In
+ certain situations, the former is cheaper. This is controlled by the
+ tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
+ to -1, the code flushes the whole TLB unconditionally. Otherwise,
+ for positive values of it, the kernel will use single TLB entry
+ invalidating instructions according to the following formula:
+
+ flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
+
+ If in doubt, say "N".
+
+config IOMMU_DEBUG
+ bool "Enable IOMMU debugging"
+ depends on GART_IOMMU && DEBUG_KERNEL
+ depends on X86_64
+ ---help---
+ Force the IOMMU to on even when you have less than 4GB of
+ memory and add debugging code. On overflow always panic. And
+ allow to enable IOMMU leak tracing. Can be disabled at boot
+ time with iommu=noforce. This will also enable scatter gather
+ list merging. Currently not recommended for production
+ code. When you use it make sure you have a big enough
+ IOMMU/AGP aperture. Most of the options enabled by this can
+ be set more finegrained using the iommu= command line
+ options. See Documentation/x86/x86_64/boot-options.txt for more
+ details.
+
+config IOMMU_STRESS
+ bool "Enable IOMMU stress-test mode"
+ ---help---
+ This option disables various optimizations in IOMMU related
+ code to do real stress testing of the IOMMU code. This option
+ will cause a performance drop and should only be enabled for
+ testing.
+
+config IOMMU_LEAK
+ bool "IOMMU leak tracing"
+ depends on IOMMU_DEBUG && DMA_API_DEBUG
+ ---help---
+ Add a simple leak tracer to the IOMMU code. This is useful when you
+ are debugging a buggy device driver that leaks IOMMU mappings.
+
+config HAVE_MMIOTRACE_SUPPORT
+ def_bool y
+
+config X86_DECODER_SELFTEST
+ bool "x86 instruction decoder selftest"
+ depends on DEBUG_KERNEL && KPROBES
+ depends on !COMPILE_TEST
+ ---help---
+ Perform x86 instruction decoder selftests at build time.
+ This option is useful for checking the sanity of x86 instruction
+ decoder code.
+ If unsure, say "N".
+
+#
+# IO delay types:
+#
+
+config IO_DELAY_TYPE_0X80
+ int
+ default "0"
+
+config IO_DELAY_TYPE_0XED
+ int
+ default "1"
+
+config IO_DELAY_TYPE_UDELAY
+ int
+ default "2"
+
+config IO_DELAY_TYPE_NONE
+ int
+ default "3"
+
+choice
+ prompt "IO delay type"
+ default IO_DELAY_0X80
+
+config IO_DELAY_0X80
+ bool "port 0x80 based port-IO delay [recommended]"
+ ---help---
+ This is the traditional Linux IO delay used for in/out_p.
+ It is the most tested hence safest selection here.
+
+config IO_DELAY_0XED
+ bool "port 0xed based port-IO delay"
+ ---help---
+ Use port 0xed as the IO delay. This frees up port 0x80 which is
+ often used as a hardware-debug port.
+
+config IO_DELAY_UDELAY
+ bool "udelay based port-IO delay"
+ ---help---
+ Use udelay(2) as the IO delay method. This provides the delay
+ while not having any side-effect on the IO port space.
+
+config IO_DELAY_NONE
+ bool "no port-IO delay"
+ ---help---
+ No port-IO delay. Will break on old boxes that require port-IO
+ delay for certain operations. Should work on most new machines.
+
+endchoice
+
+if IO_DELAY_0X80
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_0X80
+endif
+
+if IO_DELAY_0XED
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_0XED
+endif
+
+if IO_DELAY_UDELAY
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_UDELAY
+endif
+
+if IO_DELAY_NONE
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_NONE
+endif
+
+config DEBUG_BOOT_PARAMS
+ bool "Debug boot parameters"
+ depends on DEBUG_KERNEL
+ depends on DEBUG_FS
+ ---help---
+ This option will cause struct boot_params to be exported via debugfs.
+
+config CPA_DEBUG
+ bool "CPA self-test code"
+ depends on DEBUG_KERNEL
+ ---help---
+ Do change_page_attr() self-tests every 30 seconds.
+
+config OPTIMIZE_INLINING
+ bool "Allow gcc to uninline functions marked 'inline'"
+ ---help---
+ This option determines if the kernel forces gcc to inline the functions
+ developers have marked 'inline'. Doing so takes away freedom from gcc to
+ do what it thinks is best, which is desirable for the gcc 3.x series of
+ compilers. The gcc 4.x series have a rewritten inlining algorithm and
+ enabling this option will generate a smaller kernel there. Hopefully
+ this algorithm is so good that allowing gcc 4.x and above to make the
+ decision will become the default in the future. Until then this option
+ is there to test gcc for this.
+
+ If unsure, say N.
+
+config DEBUG_NMI_SELFTEST
+ bool "NMI Selftest"
+ depends on DEBUG_KERNEL && X86_LOCAL_APIC
+ ---help---
+ Enabling this option turns on a quick NMI selftest to verify
+ that the NMI behaves correctly.
+
+ This might help diagnose strange hangs that rely on NMI to
+ function properly.
+
+ If unsure, say N.
+
+config DEBUG_IMR_SELFTEST
+ bool "Isolated Memory Region self test"
+ default n
+ depends on INTEL_IMR
+ ---help---
+ This option enables automated sanity testing of the IMR code.
+ Some simple tests are run to verify IMR bounds checking, alignment
+ and overlapping. This option is really only useful if you are
+ debugging an IMR memory map or are modifying the IMR code and want to
+ test your changes.
+
+ If unsure say N here.
+
+config X86_DEBUG_STATIC_CPU_HAS
+ bool "Debug alternatives"
+ depends on DEBUG_KERNEL
+ ---help---
+ This option causes additional code to be generated which
+ fails if static_cpu_has() is used before alternatives have
+ run.
+
+ If unsure, say N.
+
+endmenu