| # SPDX-License-Identifier: GPL-2.0 |
| |
| config TRACE_IRQFLAGS_SUPPORT |
| def_bool y |
| |
| config EARLY_PRINTK_USB |
| bool |
| |
| 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 say 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 |
| select EARLY_PRINTK_USB |
| ---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 say 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 EARLY_PRINTK_USB_XDBC |
| bool "Early printk via the xHCI debug port" |
| depends on EARLY_PRINTK && PCI |
| select EARLY_PRINTK_USB |
| ---help--- |
| Write kernel log output directly into the xHCI debug port. |
| |
| One use for this feature is kernel debugging, for example when your |
| machine crashes very early before the regular console code is |
| initialized. Other uses include simpler, lockless logging instead of |
| a full-blown printk console driver + klogd. |
| |
| For normal production environments this is normally not recommended, |
| because it doesn't feed events into klogd/syslogd and doesn't try to |
| print anything on the screen. |
| |
| You should normally say N here, unless you want to debug early |
| crashes or need a very simple printk logging facility. |
| |
| config MCSAFE_TEST |
| def_bool n |
| |
| config X86_PTDUMP_CORE |
| def_bool n |
| |
| config X86_PTDUMP |
| tristate "Export kernel pagetable layout to userspace via debugfs" |
| depends on DEBUG_KERNEL |
| select DEBUG_FS |
| select X86_PTDUMP_CORE |
| ---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 |
| select X86_PTDUMP_CORE |
| ---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_WX |
| bool "Warn on W+X mappings at boot" |
| select X86_PTDUMP_CORE |
| ---help--- |
| Generate a warning if any W+X mappings are found at boot. |
| |
| This is useful for discovering cases where the kernel is leaving |
| W+X mappings after applying NX, as such mappings are a security risk. |
| |
| Look for a message in dmesg output like this: |
| |
| x86/mm: Checked W+X mappings: passed, no W+X pages found. |
| |
| or like this, if the check failed: |
| |
| x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. |
| |
| Note that even if the check fails, your kernel is possibly |
| still fine, as W+X mappings are not a security hole in |
| themselves, what they do is that they make the exploitation |
| of other unfixed kernel bugs easier. |
| |
| There is no runtime or memory usage effect of this option |
| once the kernel has booted up - it's a one time check. |
| |
| If in doubt, say "Y". |
| |
| 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_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 DEBUG_ENTRY |
| bool "Debug low-level entry code" |
| depends on DEBUG_KERNEL |
| ---help--- |
| This option enables sanity checks in x86's low-level entry code. |
| Some of these sanity checks may slow down kernel entries and |
| exits or otherwise impact performance. |
| |
| 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_FPU |
| bool "Debug the x86 FPU code" |
| depends on DEBUG_KERNEL |
| default y |
| ---help--- |
| If this option is enabled then there will be extra sanity |
| checks and (boot time) debug printouts added to the kernel. |
| This debugging adds some small amount of runtime overhead |
| to the kernel. |
| |
| If unsure, say N. |
| |
| config PUNIT_ATOM_DEBUG |
| tristate "ATOM Punit debug driver" |
| depends on PCI |
| select DEBUG_FS |
| select IOSF_MBI |
| ---help--- |
| This is a debug driver, which gets the power states |
| of all Punit North Complex devices. The power states of |
| each device is exposed as part of the debugfs interface. |
| The current power state can be read from |
| /sys/kernel/debug/punit_atom/dev_power_state |
| |
| choice |
| prompt "Choose kernel unwinder" |
| default UNWINDER_ORC if X86_64 |
| default UNWINDER_FRAME_POINTER if X86_32 |
| ---help--- |
| This determines which method will be used for unwinding kernel stack |
| traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, |
| livepatch, lockdep, and more. |
| |
| config UNWINDER_ORC |
| bool "ORC unwinder" |
| depends on X86_64 |
| select STACK_VALIDATION |
| ---help--- |
| This option enables the ORC (Oops Rewind Capability) unwinder for |
| unwinding kernel stack traces. It uses a custom data format which is |
| a simplified version of the DWARF Call Frame Information standard. |
| |
| This unwinder is more accurate across interrupt entry frames than the |
| frame pointer unwinder. It also enables a 5-10% performance |
| improvement across the entire kernel compared to frame pointers. |
| |
| Enabling this option will increase the kernel's runtime memory usage |
| by roughly 2-4MB, depending on your kernel config. |
| |
| config UNWINDER_FRAME_POINTER |
| bool "Frame pointer unwinder" |
| select FRAME_POINTER |
| ---help--- |
| This option enables the frame pointer unwinder for unwinding kernel |
| stack traces. |
| |
| The unwinder itself is fast and it uses less RAM than the ORC |
| unwinder, but the kernel text size will grow by ~3% and the kernel's |
| overall performance will degrade by roughly 5-10%. |
| |
| This option is recommended if you want to use the livepatch |
| consistency model, as this is currently the only way to get a |
| reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE). |
| |
| config UNWINDER_GUESS |
| bool "Guess unwinder" |
| depends on EXPERT |
| depends on !STACKDEPOT |
| ---help--- |
| This option enables the "guess" unwinder for unwinding kernel stack |
| traces. It scans the stack and reports every kernel text address it |
| finds. Some of the addresses it reports may be incorrect. |
| |
| While this option often produces false positives, it can still be |
| useful in many cases. Unlike the other unwinders, it has no runtime |
| overhead. |
| |
| endchoice |
| |
| config FRAME_POINTER |
| depends on !UNWINDER_ORC && !UNWINDER_GUESS |
| bool |