| 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 EMBEDDED |
| 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 DEBUG_STACKOVERFLOW |
| bool "Check for stack overflows" |
| depends on DEBUG_KERNEL |
| help |
| This option will cause messages to be printed if free stack space |
| drops below a certain limit. |
| |
| config DEBUG_STACK_USAGE |
| bool "Stack utilization instrumentation" |
| depends on DEBUG_KERNEL |
| help |
| Enables the display of the minimum amount of free stack which each |
| task has ever had available in the sysrq-T and sysrq-P debug output. |
| |
| This option will slow down process creation somewhat. |
| |
| config DEBUG_PAGEALLOC |
| bool "Debug page memory allocations" |
| depends on DEBUG_KERNEL |
| help |
| Unmap pages from the kernel linear mapping after free_pages(). |
| This results in a large slowdown, but helps to find certain types |
| of memory corruptions. |
| |
| config DEBUG_PER_CPU_MAPS |
| bool "Debug access to per_cpu maps" |
| depends on DEBUG_KERNEL |
| depends on X86_SMP |
| default n |
| help |
| Say Y to verify that the per_cpu map being accessed has |
| been setup. Adds a fair amount of code to kernel memory |
| and decreases performance. |
| |
| Say N if unsure. |
| |
| 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 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 DIRECT_GBPAGES |
| bool "Enable gbpages-mapped kernel pagetables" |
| depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64 |
| help |
| Enable gigabyte pages support (if the CPU supports it). This can |
| improve the kernel's performance a tiny bit by reducing TLB |
| pressure. |
| |
| This is experimental code. |
| |
| If in doubt, say "N". |
| |
| config DEBUG_RODATA_TEST |
| bool "Testcase for the DEBUG_RODATA feature" |
| depends on DEBUG_RODATA |
| 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_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 4KSTACKS |
| bool "Use 4Kb for kernel stacks instead of 8Kb" |
| depends on X86_32 |
| help |
| If you say Y here the kernel will use a 4Kb stacksize for the |
| kernel stack attached to each process/thread. This facilitates |
| running more threads on a system and also reduces the pressure |
| on the VM subsystem for higher order allocations. This option |
| will also use IRQ stacks to compensate for the reduced stackspace. |
| |
| config DOUBLEFAULT |
| default y |
| bool "Enable doublefault exception handler" if EMBEDDED |
| depends on X86_32 |
| 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 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_64/boot-options.txt for more |
| details. |
| |
| config IOMMU_LEAK |
| bool "IOMMU leak tracing" |
| depends on DEBUG_KERNEL |
| depends on IOMMU_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 MMIOTRACE_HOOKS |
| bool |
| |
| config MMIOTRACE |
| bool "Memory mapped IO tracing" |
| depends on DEBUG_KERNEL && PCI |
| select TRACING |
| select MMIOTRACE_HOOKS |
| help |
| Mmiotrace traces Memory Mapped I/O access and is meant for |
| debugging and reverse engineering. It is called from the ioremap |
| implementation and works via page faults. Tracing is disabled by |
| default and can be enabled at run-time. |
| |
| See Documentation/tracers/mmiotrace.txt. |
| If you are not helping to develop drivers, say N. |
| |
| config MMIOTRACE_TEST |
| tristate "Test module for mmiotrace" |
| depends on MMIOTRACE && m |
| help |
| This is a dumb module for testing mmiotrace. It is very dangerous |
| as it will write garbage to IO memory starting at a given address. |
| However, it should be safe to use on e.g. unused portion of VRAM. |
| |
| Say N, unless you absolutely know what you are doing. |
| |
| # |
| # 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 |
| disabling this option will generate a smaller kernel there. Hopefully |
| this algorithm is so good that allowing gcc4 to make the decision can |
| become the default in the future, until then this option is there to |
| test gcc for this. |
| |
| If unsure, say N. |
| |
| endmenu |
| |
