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USAGE: crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form) crash [OPTION]... [NAMELIST] (live system form) OPTIONS: NAMELIST This is a pathname to an uncompressed kernel image (a vmlinux file), or a Xen hypervisor image (a xen-syms file) which has been compiled with the "-g" option. If using the dumpfile form, a vmlinux file may be compressed in either gzip or bzip2 formats. MEMORY-IMAGE A kernel core dump file created by the netdump, diskdump, LKCD kdump, xendump or kvmdump facilities. If a MEMORY-IMAGE argument is not entered, the session will be invoked on the live system, which typically requires root privileges because of the device file used to access system RAM. By default, /dev/crash will be used if it exists. If it does not exist, then /dev/mem will be used; but if the kernel has been configured with CONFIG_STRICT_DEVMEM, then /proc/kcore will be used. It is permissible to explicitly enter /dev/crash, /dev/mem or /proc/kcore. An @ADDRESS value must be appended to the MEMORY-IMAGE if the dumpfile is a raw RAM dumpfile that has no header information describing the file contents. Multiple MEMORY-IMAGE@ADDRESS ordered pairs may be entered, with each dumpfile containing a contiguous block of RAM, where the ADDRESS value is the physical start address of the block expressed in hexadecimal. The physical address value(s) will be used to create a temporary ELF header in /var/tmp, which will only exist during the crash session. If a raw RAM dumpile represents a live memory source, such as that specified by the QEMU mem-path argument of a memory-backend-file object, then "live:" must be prepended to the MEMORY-IMAGE name. mapfile If the NAMELIST file is not the same kernel that is running (live system form), or the kernel that was running when the system crashed (dumpfile form), then the System.map file of the original kernel should be entered on the command line. -h [option] --help [option] Without an option argument, display a crash usage help message. If the option argument is a crash command name, the help page for that command is displayed. If it is the string "input", a page describing the various crash command line input options is displayed. If it is the string "output", a page describing command line output options is displayed. If it is the string "all", then all of the possible help messages are displayed. After the help message is displayed, crash exits. -s Silently proceed directly to the "crash>" prompt without displaying any version, GPL, or crash initialization data during startup, and by default, runtime command output is not passed to any scrolling command. -i file Execute the command(s) contained in "file" prior to displaying the "crash>" prompt for interactive user input. -d num Set the internal debug level. The higher the number, the more debugging data will be printed when crash initializes and runs. -S Use /boot/System.map as the mapfile. -e vi | emacs Set the readline(3) command line editing mode to "vi" or "emacs". The default editing mode is "vi". -f Force the usage of a compressed vmlinux file if its original name does not start with "vmlinux". -k Indicate that the NAMELIST file is an LKCD "Kerntypes" debuginfo file. -g [namelist] Determine if a vmlinux or xen-syms namelist file contains debugging data. -t Display the system-crash timestamp and exit. -L Attempt to lock all of its virtual address space into memory by calling mlockall(MCL_CURRENT|MCL_FUTURE) during initialization. If the system call fails, an error message will be displayed, but the session continues. -c tty-device Open the tty-device as the console used for debug messages. -p page-size If a processor's page size cannot be determined by the dumpfile, and the processor default cannot be used, use page-size. -o filename Only used with the MEMORY-IMAGE@ADDRESS format for raw RAM dumpfiles, specifies a filename of a new ELF vmcore that will be created and used as the dumpfile. It will be saved to allow future use as a standalone vmcore, replacing the original raw RAM dumpfile. -m option=value --machdep option=value Pass an option and value pair to machine-dependent code. These architecture-specific option/pairs should only be required in very rare circumstances: X86_64: phys_base=<physical-address> irq_eframe_link=<value> max_physmem_bits=<value> kernel_image_size=<value> vm=orig (pre-2.6.11 virtual memory address ranges) vm=2.6.11 (2.6.11 and later virtual memory address ranges) vm=xen (Xen kernel virtual memory address ranges) vm=xen-rhel4 (RHEL4 Xen kernel virtual address ranges) PPC64: vm=orig vm=2.6.14 (4-level page tables) IA64: phys_start=<physical-address> init_stack_size=<size> vm=4l (4-level page tables) ARM: phys_base=<physical-address> ARM64: phys_offset=<physical-address> kimage_voffset=<kimage_voffset-value> X86: page_offset=<CONFIG_PAGE_OFFSET-value> -x Automatically load extension modules from a particular directory. The directory is determined by the following order of precedence: (1) the directory specified in the CRASH_EXTENSIONS shell environment variable (2) /usr/lib64/crash/extensions (64-bit architectures) (3) /usr/lib/crash/extensions (32-bit architectures) (4) the ./extensions subdirectory of the current directory --active Track only the active task on each cpu. --buildinfo Display the crash binary's build date, the user ID of the builder, the hostname of the machine where the build was done, the target architecture, the version number, and the compiler version. --memory_module modname Use the modname as an alternative kernel module to the crash.ko module that creates the /dev/crash device. --memory_device device Use device as an alternative device to the /dev/crash, /dev/mem or /proc/kcore devices. --log dumpfile Dump the contents of the kernel log buffer. A kernel namelist argument is not necessary, but the dumpfile must contain the VMCOREINFO data taken from the original /proc/vmcore ELF header. --no_kallsyms Do not use kallsyms-generated symbol information contained within kernel module object files. --no_modules Do not access or display any kernel module related information. --no_ikconfig Do not attempt to read configuration data that was built into kernels configured with CONFIG_IKCONFIG. --no_data_debug Do not verify the validity of all structure member offsets and structure sizes that it uses. --no_kmem_cache Do not initialize the kernel's slab cache infrastructure, and commands that use kmem_cache-related data will not work. --no_elf_notes Do not use the registers from the ELF NT_PRSTATUS notes saved in a compressed kdump header for backtraces. --kmem_cache_delay Delay the initialization of the kernel's slab cache infrastructure until it is required by a run-time command. --readnow Pass this flag to the embedded gdb module, which will override the two-stage strategy that it uses for reading symbol tables from the NAMELIST. If module symbol tables are loaded during runtime with the "mod" command, the same override will occur. --smp Specify that the system being analyzed is an SMP kernel. -v --version Display the version of the crash utility, the version of the embedded gdb module, GPL information, and copyright notices. --cpus number Specify the number of cpus in the SMP system being analyzed. --osrelease dumpfile Display the OSRELEASE vmcoreinfo string from a kdump dumpfile header. --hyper Force the session to be that of a Xen hypervisor. --p2m_mfn pfn When a Xen Hypervisor or its dom0 kernel crashes, the dumpfile is typically analyzed with either the Xen hypervisor or the dom0 kernel. It is also possible to analyze any of the guest domU kernels if the pfn_to_mfn_list_list pfn value of the guest kernel is passed on the command line along with its NAMELIST and the dumpfile. --xen_phys_start physical-address Supply the base physical address of the Xen hypervisor's text and static data for older xendump dumpfiles that did not pass that information in the dumpfile header. --zero_excluded If the makedumpfile(8) facility has filtered a compressed kdump dumpfile to exclude various types of non-essential pages, or has marked a compressed or ELF kdump dumpfile as incomplete due to an ENOSPC or other error during its creation, any attempt to read missing pages will fail. With this flag, reads from any of those pages will return zero-filled memory. --no_panic Do not attempt to find the task that was running when the kernel crashed. Set the initial context to that of the "swapper" task on cpu 0. --more Use /bin/more as the command output scroller, overriding the default of /usr/bin/less and any settings in either ./.crashrc or $HOME/.crashrc. --less Use /usr/bin/less as the command output scroller, overriding any settings in either ./.crashrc or $HOME/.crashrc. --CRASHPAGER Use the output paging command defined in the CRASHPAGER shell environment variable, overriding any settings in either ./.crashrc or $HOME/.crashrc. --no_scroll Do not pass run-time command output to any scrolling command. --no_strip Do not strip cloned kernel text symbol names. --no_crashrc Do not execute the commands in either $HOME/.crashrc or ./.crashrc. --mod directory When loading the debuginfo data of kernel modules with the "mod -S" command, search for their object files in directory instead of in the standard location. --src directory Search for the kernel source code in directory instead of in the standard location that is compiled into the debuginfo data. --reloc size When analyzing live x86 kernels configured with a CONFIG_PHYSICAL_START value that is larger than its CONFIG_PHYSICAL_ALIGN value, then it will be necessary to enter a relocation size equal to the difference between the two values. --hash count Set the number of internal hash queue heads used for list gathering and verification. The default count is 32768. --kaslr offset | auto If an x86 or x86_64 kernel was configured with CONFIG_RANDOMIZE_BASE, the offset value is equal to the difference between the symbol values compiled into the vmlinux file and their relocated KASLR value. If set to auto, the KASLR offset value will be automatically calculated. --minimal Bring up a session that is restricted to the log, dis, rd, sym, eval, set and exit commands. This option may provide a way to extract some minimal/quick information from a corrupted or truncated dumpfile, or in situations where one of the several kernel subsystem initialization routines would abort the crash session. --kvmhost [32|64] When examining an x86 KVM guest dumpfile, this option specifies that the KVM host that created the dumpfile was an x86 (32-bit) or an x86_64 (64-bit) machine, overriding the automatically determined value. --kvmio <size> override the automatically-calculated KVM guest I/O hole size. --offline [show|hide] Show or hide command output that is associated with offline cpus, overriding any settings in either ./.crashrc or $HOME/.crashrc. FILES: .crashrc Initialization commands. The file can be located in the user's HOME directory and/or the current directory. Commands found in the .crashrc file in the HOME directory are executed before those in the current directory's .crashrc file. ENVIRONMENT VARIABLES: EDITOR Command input is read using readline(3). If EDITOR is set to emacs or vi then suitable keybindings are used. If EDITOR is not set, then vi is used. This can be overridden by "set vi" or "set emacs" commands located in a .crashrc file, or by entering "-e emacs" on the crash command line. CRASHPAGER If CRASHPAGER is set, its value is used as the name of the program to which command output will be sent. If not, then command output output is sent to "/usr/bin/less -E -X" by default. CRASH_MODULE_PATH Specifies an alternative directory tree to search for kernel module object files. CRASH_EXTENSIONS Specifies a directory containing extension modules that will be loaded automatically if the -x command line option is used.