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[@ADDRESS]
A kernel core dump file created by the netdump, diskdump,
LKCD kdump, xendump kvmdump or VMware 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.
As VMware facility, the crash utility is able to process
VMware VM memory dump generated by VM suspend or guest
core dump. In that case, .vmss or .guest file should be
used as a MEMORY-IMAGE and .vmem file must be located in
the same folder.
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>
irq_stack_gap=<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)
vm=5level (5-level page tables)
page_offset=<PAGE_OFFSET-value>
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>
max_physmem_bits=<value>
vabits_actual=<value>
X86:
page_offset=<CONFIG_PAGE_OFFSET-value>
-x Automatically load extension modules from a particular
directory. If a directory is specified in the
CRASH_EXTENSIONS shell environment variable, then that
directory will be used. Otherwise
/usr/lib64/crash/extensions (64-bit architectures) or
/usr/lib/crash/extensions (32-bit architectures) will be
used; if they do not exist, then the ./extensions
directory will be used.
--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_ikconf
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 its two-stage strategy that it uses for reading
symbol tables from the NAMELIST.
--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.
--hex Set the default command output radix to 16, overriding the
default radix of 10, and any radix settings in either
./.crashrc or $HOME/.crashrc.
--dec Set the default command output radix to 10, overriding any
radix settings in either ./.crashrc or $HOME/.crashrc.
This is the default radix setting.
--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.
--kaslr offset|auto
If an 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 values. If set to
auto, the KASLR offset value will be automatically
calculated.
--reloc size
When analyzing live x86 kernels that were 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.
--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 related to offline
cpus. The default setting is show.
