ksymoops extracts kernel Oops reports from the Oops.file and uses
various sources of symbol information to convert the addresses and code
to meaningful text. Reporting a kernel Oops is meaningless on its own
because other people do not know what your kernel looks like, you need
to feed the Oops text through ksymoops then send the ksymoops output as
part of your bug report.
The ksymoops executable is meant to be run whenever you have Oops to
report. The original Oops text can come from anywhere. Typically it
is in a file created by your syslogd(8). If syslogd is not available,
the log might be available via dmesg(8). If you are running a serial
console (see linux/Documentation/serial-console.txt) then you can
capture the Oops text on another machine. If all else fails, copy the
Oops by hand from the screen, reboot and enter it by hand.
ksymoops can be run by anybody who has read access to the various input
files. It does not have to be run as root.
OPTIONS
Some of the options have default values that are set in the Makefile.
The text below describes the standard defaults but your distribution
may have been modified to use different defaults. If in doubt,
ksymoops -h will list the current defaults.
The first 10 options (-v, -V, -k, -K, -l,
-L, -o, -O, -m, -M or the corresponding
long forms) are 5 pairs. The lower case options (vklom) take a value
and turn the option on, the upper case options (VKLOM) take no value
and turn the option off. If you specify both lower and upper case
versions of the same option then the last one is used but you are
warned that it may not be what you intended.
ksymoops will run quite happily with no options. However there is a
risk that the default values for the symbol sources may not be
suitable. Therefore if none of
-v vmlinux, -V,
-k ksyms, -K,
-l lsmod, -L,
-o object, -O,
-m system.map or -M
are specified, ksymoops prints a warning message.
You did not tell me where to find symbol information. I will assume
that the log matches the kernel and modules that are running right now
and I'll use the default options above for symbol resolution.
If the current kernel and/or modules do not match the log, you can get
more accurate output by telling me the kernel version and where to find
map, modules, ksyms etc. ksymoops -h explains the options.
If any of the
-v vmlinux,
-k ksyms,
-l lsmod,
-o object or
-m system.map
options contain the string *r (*m, *n, *s) then the string is replaced
at run time by the current value of `uname -r` (-m, -n, -s). This is
mainly intended to let ksymoops automatically pick up version dependent
files using its default parameters, however it could be used by bug
reporting scripts to automatically pick up files whose name or
directory depends on the current kernel.
-v vmlinux--vmlinux=vmlinux
Name of the vmlinux file that corresponds to the failing kernel.
Note: This is the vmlinux file, not zImage, bzImage, vmlinuz
etc. Typically this would be /usr/src/linux/vmlinux. If you specify
-v, you should only specify it once.
-V--no-vmlinux
Do not read any vmlinux file.
Default is -V.
-k ksyms--ksyms=ksyms
Where to find the list of kernel symbols at the time of the failure.
Unfortunately the kernel symbol list in /proc/ksyms is volatile, it is
updated as modules are loaded and removed. Try to copy /proc/ksyms to
a normal file as soon as possible after the Oops and point ksymoops at
that copy using -k. Modutils has support for automatically
copying ksyms and lsmod data, see insmod(8). If you had to reboot
after the Oops and you do not have a copy of /proc/ksyms at the time of
the Oops, try to reload the same modules in the same order before
running ksymoops. If you specify -k, you should only specify it
once.
-K--no-ksyms
Do not read any kernel symbols.
Default is -k /proc/ksyms.
-l lsmod--lsmod=lsmod
Where to find the list of loaded modules at the time of the failure.
Unfortunately the list in /proc/modules is volatile, it is updated as
modules are loaded and removed. Try to copy /proc/modules to a normal
file as soon as possible after the Oops and point ksymoops at that copy
using -l. Modutils has support for automatically copying ksyms
and lsmod data, see insmod(8). If you had to reboot after the Oops and
you do not have a copy of /proc/modules at the time of the Oops, try to
reload the same modules in the same order before running ksymoops. If
you specify -l, you should only specify it once.
-L--no-lsmod
Do not read any list of loaded modules.
Default is -l /proc/modules.
-o object--object=object
Where to find the objects for modules used by the failing kernel. This
can be a directory name or an individual file. If it is a directory
then ksymoops does a recursive find(1) in that directory for all files
matching '*.o'. -o can be specified more than once, the list is
cumulative and can contain a mixture of directories and files.
Note: When you specify a directory, ksymoops only uses files that
end in '.o'. Any modules with non-standard names are ignored unless
you specify those files explicitly. For example, if vmnet and vmmon
modules do not end in '.o', you need something like this to pick up all
the normal modules plus the non-standard names.
If you are using a version of insmod(8) that stores the module filename
in /proc/ksyms, ksymoops can go directly to that file, it does not need
-o. The -o option is only used when ksyms contains at
least one module whose filename is not explicitly listed in ksyms.
-O--no-object
Do not scan for any objects. If /proc/ksyms is supplied and insmod
added the ksymoops assistance symbols (starting with __insmod) then
those symbols are used to access the objects, no directory scanning is
done so neither -o nor -O have any effect. To completely disable the
use of module objects when ksyms contains __insmod symbols, specify -O
and one of -i or -I.
Default is -o /lib/modules/*r/. For example, if
uname -r reports 2.2.7, ksymoops uses
-o /lib/modules/2.2.7/, but only if it does not already know
where the objects are.
-m system.map--system-map=system.map
Where to find the System.map corresponding to the failing kernel.
-M--no-system-map
Do not read any System.map.
Default is -m /usr/src/linux/System.map.
-s save.map--save-map=save.map
After ksymoops reads all its sources of symbols, it generates an
internal system map which contains everything from System.map plus a
best attempt to extract all symbols from all the loaded modules. If
you want to see that consolidated map, specify -s save.map to
write it out to save.map. You do not need to save the map for
normal bug reporting.
Default is no saved map.
-S--short-lines
Some of the ksymoops output lines can be quite long, especially in the
code disassembly, but if you have a wide screen the ksymoops output is
easier to read as long lines. The -S toggle switches between
short and long lines. Note that lines printed by the kernel and
extracted from the Oops.file are not affected by -S, problem text
is printed as is.
Default is short lines.
-e--endian-swap
ksymoops extracts code bytes from the reports and converts them to
instructions. All kernels print code bytes in hex but unfortunately
some systems print multiple bytes using the native machine endianess.
This only causes a problem if the code is printed in anything other
than 1 byte chunks. For example, i386 prints one byte at a time which
is machine portable, alpha prints 4 bytes at a time in native endianess
and the report is not machine portable.
If you are doing cross system Oops diagnosis (say for a new system or
an embedded version of Linux), then the failing system and the
reporting system can have different endianess. On systems that support
little and big endianess at the same time, ksymoops could be compiled
with one endianess but the kernel dump could be using another. If your
code disassembly is wrong, specify -e. The -e toggles
between native and reverse endianess when reading the bytes in each
chunk of code. In this context, a chunk of code is 4 or 8 hex digits
(2 or 4 bytes of code), -e has no effect on code that is printed
as 2 hex digits (one byte at a time).
Note: Earlier versions of ksymoops used a
-c code_bytes option. That is now obsolete, use -e
instead, but only when the code disassembly is incorrect.
The default is to read code bytes using the endianess that ksymoops was
compiled with.
-x--hex
Normally, ksymoops prints offsets and lengths in hex. If you want
offsets and lengths to be printed in decimal, use the -x toggle.
Default is hex.
-1--one-shot
Normally, ksymoops reads its entire input file and extracts all Oops
reports. If the -1 toggle is set, it will run in one shot mode and
exit after the first Oops. This is useful for automatically mailing
reports as they happen, like this :-
#!/bin/sh
# ksymoops1
while (true)
do
ksymoops -1 > $HOME/oops1
if [ $? -eq 3 ]
then
exit 0 # end of input, no Oops found
fi
mail -s Oops admin < $HOME/oops1
done
tail -f /var/log/messages | ksymoops1
Restarting the tail command after log rotation is left as an exercise
for the reader.
In one shot mode, reading of the various symbol sources is delayed
until ksymoops sees the first program counter, call trace or code line.
This ensures that the current module information is used. The downside
is that any parameter errors are not detected until an Oops actually
occurs.
The default is to read everything from the Oops.file, extracting and
processing every Oops it finds. Note that the default method reads the
symbol sources once and assumes that the environment does not change
from one Oops to the next, not necessarily valid when you are using
modules.
-i--ignore-insmod-path
When you are using an initial ramdisk for modules, the path name to the
modules is typically just /lib. That pathname is recorded in the
__insmod..._O symbol in ksyms but ksymoops cannot find the files in the
real /lib, so it issues warning messages. If you specify -i then
ksymoops ignores the path name in __insmod...O symbols, instead it
searchs the -o paths (if any) looking for the object with the correct
basename and timestamp. -i is recommended when loading modules from a
ramdisk. This assumes that the -o paths contain the modules used to
build the ramdisk, with the same timestamp.
Default is to use the path from __insmod...O symbols.
-T--ignore-insmod-all
Use this toggle if you want to completely ignore all insmod(8) assistance
information (symbols starting with __insmod in ksyms). This includes
module paths, timestamps, section start and length etc. Then ksymoops
will fall back on the old method of matching symbols to module objects,
using the -o paths (if any). It is hard to think of a legitimate
reason to use -I, -i is better if your only problem is a path name
mismatch.
Default is to use the path from __insmod...O symbols and section
information from __insmod...S symbols.
-T truncate--truncate=truncate
If your binutils are configured for multiple targets, they tend to
print addresses using the address size of the largest target. If the
other inputs to ksymoops have shorter symbol sizes, the different
representations cause symbols which should have the same address to
appear at different addresses. This is a particular problem when
building for mixed 32 and 64 bit targets. To remove the ambiguity,
use --truncate=truncate. A value of 0 means no truncation, a
value greater than 8*sizeof(unsigned long) is silently converted to 0.
Default is --truncate=0, no truncation.
-d--debug
Each occurrence of -d increases the debugging level of ksymoops
by one.
Level 1
Regular expression compile summaries.
Before and after text for *[mns] expansion.
Option processing, but only for options appearing after -d.
Entry to the main processing routines.
KSYMOOPS_ environment variables.
Object files extracted directly from ksyms.
Information on matches between loaded modules and module objects.
Filename of the Oops report.
Version number for the oops.
Saving merged system map.
Level 2
Summary information on symbol table sizes.
Every version number found in the oops.
Comparing symbol maps.
Appending symbol maps.
Full pathname of a program.
External commands issued.
Progress reports for -o object.
The names of '*.o' files found in a -o directory.
Offset adjustments for module sections.
Every line output from running objdump on the code bytes.
Level 3
Every input line from Oops.file.
Non-duplicate and low address symbols dropped from the merged system map.
Mapping of addresses to symbols.
Level 4
Every input line from all sources, this prints duplicate lines.
The return code from every regexec call.
Ambiguous matches that are ignored.
Every symbol added to every table.
Copying symbol tables.
Increases in symbol table sizes.
Entry to some lower level routines.
Every symbol dropped.
Level 5
For matching regexecs, details on every substring.
Default is no debugging.
-h--help
Prints the help text and the current defaults.
-t target--target=target
Normally you do Oops diagnosis using the same hardware as the Oops
itself. But sometimes you need to do cross system Oops diagnosis,
taking an Oops from one type of hardware and processing it on an
another. For example, when you are porting to a new system or you are
building an embedded kernel. To do cross system Oops processing, you
must tell ksymoops what the target hardware is, using
-t target, where target is a bfd target name. You can
find out which targets your machine supports by
ksymoops -t '?'
Default is the same target as ksymoops itself, with one exception. On
sparc64, the kernel uses elf64-sparc but user programs are elf32-sparc.
If -t target was not specified and ksymoops was compiled for
elf32-sparc and the Oops contains a TPC line then ksymoops
automatically switches to -t elf64-sparc.
-a architecture--architecture=architecture
To do cross system Oops processing, you must tell ksymoops what the
target architecture is, using -a architecture, where
architecture is a bfd architecture name. You can find out which
architectures your machine supports by
ksymoops -a '?'
Default is the same architecture as ksymoops itself, with one
exception. On sparc64, the kernel uses sparc:v9a but user programs are
sparc. If -a architecture was not specified and ksymoops was
compiled for sparc and the Oops contains a TPC line then ksymoops
automatically switches to -a sparcv:9a.
-A "address list"--addresses="address list" If you
have a few adhoc addresses to convert to symbols, you can specify them
explicitly using -A "address list". Any words in the list
that appear to be addresses are converted to symbols. Punctuation
characters and non-address words are silently ignored, leading 0x on
addresses is also ignored, so you can paste text including words and
only the addresses will be processed.
Oops.file ...
ksymoops accepts zero or more input files and reads them all. If no
files are specified on the command line and no addresses are supplied
via -A then ksymoops reads from standard input. You can even
type the Oops text directly at the terminal, although that is not
recommended.
INPUT
ksymoops reads the input file(s), using regular expressions to select
lines that are to be printed and further analyzed. You do not need to
extract the Oops report by hand.
All tabs are converted to spaces, assuming tabstop=8. Where the text
below says "at least one space", tabs work just as well but are
converted to spaces before printing. All nulls and carriage returns
are silently removed from input lines, both cause problems for string
handling and printing.
An input line can have a prefix which ksymoops will print as part of
the line but ignore during analysis. A prefix can be from syslogd(8)
(consisting of date, time, hostname, 'kernel:'), it can be '<n>'
from /proc/kmsg or the prefix can just be leading spaces. "start of
line" means the first character after skipping all prefixes, including
all leading space.
Every kernel architecture team uses different messages for kernel
problems, see Oops_read in oops.c for the full, gory list. If you are
entering an Oops by hand, you need to follow the kernel format as much
as possible, otherwise ksymoops may not recognize your input. Input is
not case sensitive.
A bracketed address is optional '[', required '<', at least 4 hex
digits, required '>', optional ']', optional spaces. For example
[<01234567>] or <beaf>.
An unbracketed address is at least 4 hex digits, followed by optional
spaces. For example 01234567 or abCDeF.
The sparc PC line is 'PSR:' at start of line, space, hex digits, space,
'PC:', space, unbracketed address.
The sparc64 TPC line is 'TSTATE:' at start of line, space, 16 hex
digits, space 'TPC:', space, unbracketed address.
The ppc NIP line has several formats. 'kernel pc' 'trap at PC:'
'bad area pc' or 'NIP:'. Any of those strings followed by a single
space and an unbracketed address is the NIP value.
The mips PC line is 'epc' at start of line, optional space, one or more
':', optional space, unbracketed address.
The ix86 EIP line is 'EIP:' at start of line, at least one space, any
text, bracketed address.
The m68k PC line is 'PC' at start of line, optional spaces, '=',
optional spaces, bracketed address.
The arm PC line is 'pc' at start of line, optional spaces, ':',
optional spaces, bracketed address.
The IA64 IP line is ' ip', optional space, ':', optional space,
bracketed address.
A mips ra line is 'ra', optional spaces, one or more '=', optional
spaces, unbracketed address.
A sparc o7 or i7 line is 'i' or 'o', '0' or '4', ':', space, one or
more occurrences of (hex digit, space, 'iosp:'), space, ('i' or 'o',
'7') or ('ret_pc').
A sparc register dump line is ('i', '0' or '4', ':', space) or
('Instruction DUMP:', space) or ('Caller[').
The IA64 b0 line is 'b0', optional space, ':', optional space,
unbracketed address. This can be repeated for other b registers, e.g.
b6, b7.
A set of call trace lines starts with 'Trace:' or 'Call Trace:' or
'Call Backtrace:' (ppc only) or 'Function entered at' (arm only) or
'Caller[' (sparc64 only) followed by at least one space.
For 'Trace:' and 'Call Trace:', the rest of the line is bracketed
addresses, they can be continued onto extra lines. Addresses can not
be split across lines.
For 'Call Backtrace:' (ppc only), the rest of the line is unbracketed
addresses, they can be continued onto extra lines. Addresses can not
be split across lines.
For 'Function entered at' (arm only), the line contains exactly two
bracketed addresses and is not continued.
For 'Caller[' (sparc64 only), the line contains exactly one unbracketed
address and is not continued.
Spin loop information is indicated by a line starting with 'bh: ',
followed by lines containing reverse bracketed trace back addresses.
For some reason, these addresses are different from every other address
and look like this '<[hex]> <[hex]>' instead of the normal
'[<hex>] [<hex>]'.
The Code line is identified by 'Instruction DUMP' or ('Code' followed
by optional spaces), ':', one or more spaces, followed by at least one
hex value. The line can contain multiple hex values, each separated by
at least one space. Each hex value must be 2 to 8 digits and must be a
multiple of 2 digits.
Any of the code values can be enclosed in <..> or (..), the last such
value is assumed to be the failing instruction. If no value has <..>
or (..) then the first byte is assumed to be the failing instruction.
Special cases where Code: can be followed by text. 'Code: general
protection' or 'Code: <n>'. Dump the data anyway, the code was
unavailable.
Do you detect a slight note of inconsistency in the above?
ADDRESS TO SYMBOL CONVERSION
Addresses are converted to symbols based on the symbols in vmlinux,
/proc/ksyms, object files for modules and System.map, or as many of
those sources as ksymoops was told to read. ksymoops uses as many
symbol sources as you can provide, does cross checks between the
various sources to identify any discrepancies and builds a merged map
containing all symbols, including loaded modules where possible.
Symbols which end in _R_xxxxxxxx (8 hex digits) or _R_smp_xxxxxxxx are
symbol versioned, see genksyms(8). ksymoops strips the _R_... when
building its internal system map.
Module symbols do not appear in vmlinux nor System.map and only
exported symbols from modules appear in /proc/ksyms. Therefore
ksymoops tries to read module symbols from the object files specified
by -o. Without these module symbols, diagnosing a problem in a
module is almost impossible.
There are many problems with module symbols, especially with versions
of insmod(8) up to and including 2.1.121. Some modules do not export
any symbols, there is no sign of them in /proc/ksyms so they are
effectively invisible. Even when a module exports symbols, it
typically only exports one or two, not the complete list that is really
needed for Oops diagnosis. ksymoops can build a complete symbol table
from the object module but it has to
(a) Know that the module is loaded.
(b) Find the correct object file for that module.
(c) Convert section and symbol data from the module into kernel
addresses.
If a module exports no symbols then there is no way for ksymoops to
obtain any information about that module. lsmod says it is loaded but
without symbols, ksymoops cannot find the corresponding object file nor
map offsets to addresses. Sorry but that is the way it is, if you Oops
in a module that displays no symbols in ksyms, forget it :(.
When a module exports symbols, the next step is to find the object file
for that module. In most cases the loaded module and the object file
has the same basename but that is not guaranteed. For example,
insmod uart401 -o xyz
will load uart401.o from your module directories but store it as xyz.
Both ksyms and lsmod say module name 'xyz' with no indication that the
original object file was uart401. So ksymoops cannot just use the
module name from ksyms or lsmod, it has to do a lot more work to find
the correct object. It does this by looking for a unique match between
exported symbols and symbols in the module objects.
For every file obtained from the -o option(s), ksymoops extracts
all symbols (both static and external), using nm(1). It then runs the
exported module symbols in ksyms and, for every exported module symbol,
it does a string compare of that symbol against every symbol in every
object. When ksymoops finds a module symbol that is exported in ksyms
and appears exactly once amongst all the -o objects then it
has to assume that the object is the one used to load the module. If
ksymoops cannot find any match for any exported symbol in a module or
finds more than one match for every exported symbol in a module then it
cannot determine which object was actually loaded.
After ksymoops has matched a loaded module against an object using a
unique symbol, it still has to calculate addresses for the symbols from
the object. To do this, ksymoops first needs the start address of the
text, data and read only data sections in the loaded module. Given the
start address of a section, ksymoops can calculate the kernel address
of every symbol in that section and add the symbols to the combined
system map, this includes symbols that are not exported. Unfortunately
the start address of a section is only available if the module exports
at least one symbol from that section. For example, if a module only
exports text symbols (the most common case) then ksymoops can only
calculate the start of the text section and has to discard symbols from
the data and read only data sections for that module, reducing the
information available for diagnosis.
When multiple symbol sources are available and those symbol sources
contain a kernel version number, ksymoops compares all the version
numbers. It flags a warning if there is any mismatch. One of the more
common causes of problems is force loading a module from one kernel
into a different kernel. Even if it was deliberate, it needs to be
highlighted for diagnosis.
When both ksyms and lsmod are available, the list of modules extracted
from ksyms is compared against the list of modules from lsmod. Any
difference is flagged as a warning, it typically indicates invisible
modules. However it can also be caused by a mismatch between ksyms and
lsmod.
When multiple symbol sources are available, ksymoops does cross checks
between them. Each check is only performed if both symbol sources are
present and non-empty. Every symbol in the first source should appear
in the second source and should have the same address. Where there is
any discrepancy, one of the sources takes precedence, the precedence is
somewhat arbitrary. Some discrepancies are silently ignored because
they are special cases but the vast majority of symbols are expected to
match.
* Exported module symbols in ksyms are compared against the symbols
in the corresponding object file. ksyms takes precedence.
* The kernel (non module) symbols from ksyms are compared against
vmlinux. vmlinux takes precedence.
* The symbols from System.map are compared against vmlinux. vmlinux
takes precedence.
* The symbols from vmlinux are compared against System.map. vmlinux
takes precedence. These two sources are compared in both directions,
they should be identical.
* The kernel (non module) symbols from ksyms are compared against
System.map. System.map takes precedence.
After reading and cross checking all the symbol sources, they are
merged into a single system map. Duplicate symbols, registers (type a)
and static 'gcc2_compiled.' symbols are dropped from the merged map.
Any symbols with an address below 4096 are discarded, these are symbols
like Using_Versions which has an address of 0.
Given all the above processing and deduction, it is obvious that the
merged system map cannot be 100% reliable, which means that conversion
of addresses to symbols cannot be reliable. The addresses are valid
but the symbol conversion is only as good as the symbol sources you fed
into ksymoops.
/proc/ksyms and /proc/lsmod are volatile so unless ksymoops gets the
current ksyms, you always have to question the validity of the module
information. The only way I know to (almost) guarantee valid ksyms is
to use ksymoops in one shot mode (see option -1). Then ksymoops
reads the log and decodes Oops in real time.
KSYMOOPS SUPPORT IN MODUTILS
Modutils 2.3.1 onwards has support to make oops debugging easier,
especially for modules. See insmod(8) for details. If you want
automatic snapshots of ksyms and lsmod data as modules are loaded and
unloaded, create /var/log/ksymoops, it should be owned by root with
mode 644 or 600. If you do not want automatic snapshots, do not create
the directory. A script (insmod_ksymoops_clean) is provided by
modutils to delete old versions, this should be run by cron once a day.
OUTPUT
ksymoops prints all lines that contain text which might indicate a
kernel problem. Due the complete lack of standards in kernel error
messages, I cannot guarantee that all problem lines are printed. If
you see a line in your logs which ksymoops should extract but does not,
contact the maintainer.
When ksymoops sees EIP/PC/NIP/TPC lines, call trace lines or code
lines, it prints them and stores them for later processing. When the
code line is detected, ksymoops converts the EIP/PC/NIP/TPC address and
the call trace addresses to symbols. These lines have ';' after the
header instead of ':', just in case anybody wants to feed ksymoops
output back into ksymoops, these generated lines are ignored.
Formatted data for the program counter, trace and code is only output
when the Code: line is seen. If any data has been stored for later
formatting and more than 5 lines other than Oops text or end of file
are encountered then ksymoops assumes that the Code: line is missing or
garbled and dumps the formatted data anyway. That should be fail safe
because the Code: line (or its equivalent) signals the end of the Oops
report. Except for sparc64 on SMP which has a register dump
after the code. ksymoops tries to cater for this exception.
Sigh.
Addresses are converted to symbols wherever possible. For example
>>EIP; c0113f8c <sys_init_module+49c/4d0>
Trace; c011d3f5 <sys_mremap+295/370>
Trace; c011af5f <do_generic_file_read+5bf/5f0>
Trace; c011afe9 <file_read_actor+59/60>
Trace; c011d2bc <sys_mremap+15c/370>
Trace; c010e80f <do_sigaltstack+ff/1a0>
Trace; c0107c39 <overflow+9/c>
Trace; c0107b30 <tracesys+1c/23>
Trace; 00001000 Before first symbol
Each converted address is followed by the nearest symbol below that
address. That symbol is followed by the offset of the address from the
symbol. The value after '/' is the "size" of the symbol, the
difference between the symbol and the next known symbol. So
>>EIP; c0113f8c <sys_init_module+49c/4d0>
means that the program counter was c0113f8c. The previous symbol is
sys_init_module, the address is 0x49c bytes from the start of the
symbol, sys_init_module is 0x4d0 bytes long. If you prefer decimal
offsets and lengths see option -x. If the symbol comes from a
module, it is prefixed by '[module_name]', several modules have
the same procedure names.
The use of 'EIP' for program counter above is for ix86. ksymoops tries
to use the correct acronym for the program counter (PC, NIP, TPC etc.)
but if it does not recognize the target hardware, it defaults to EIP.
When a Code: line is read, ksymoops extracts the code bytes. It uses
the program counter line together with the code bytes to generate a
small object file in the target architecture. ksymoops then invokes
objdump(1) to disassemble this object file. The human readable
instructions are extracted from the objdump output and printed with
address to symbol conversion. If the disassembled code does not look
sensible, see the -e, -a and -t options.
TAKE ALL SYMBOLS, OFFSETS AND LENGTHS WITH A PINCH OF SALT!
The addresses are valid but the symbol conversion is only as good as
the input you gave ksymoops. See all the problems in "ADDRESS TO SYMBOL
CONVERSION" above. Also the stack trace is potentially ambiguous. The
kernel prints any addresses on the stack that might be valid
addresses. The kernel has no way of telling which (if any) of these
addresses are real and which are just lying on the stack from previous
procedures. ksymoops just decodes what the kernel prints.
ENVIRONMENT VARIABLES
KSYMOOPS_NM
Path for nm, defaults to /usr/bin/nm.
KSYMOOPS_FIND
Path for find, defaults to /usr/bin/find.
KSYMOOPS_OBJDUMP
Path for objdump, defaults to /usr/bin/objdump.
CROSS SYSTEM OOPS DIAGNOSIS
To process an Oops from one system on another, you need access to all
the symbol sources, including modules, System.map, ksyms etc. If the
two systems are different hardware, you also need versions of the nm
and objdump commands that run on your system but handle the target
system. You also need versions of libbfd, libopcodes, and libiberty
that handle the target system. Consult the binutils documentation
for instructions on how to build cross system versions of these
utilities.
To override the default versions of nm and find, use the environment
variables above. To use different versions of libbfd and libiberty,
use the --rpath option when linking ksymoops or the LD_LIBRARY_PATH
environment variable when running ksymoops. See the info pages for ld
and /usr/doc/glibc*/FAQ.
DIAGNOSTICS
0 - normal.
1 - error(s) or warning(s) issued, results may not be reliable.
2 - fatal error, no useful results.
3 - One shot mode, end of input was reached without seeing an Oops.
BUGS
Because of the plethora of possible kernel error and information
strings, ksymoops's pattern matching sometimes prints lines that are
not errors at all. For example, a line starting with 3c589 matches the
pattern for a call trace line, both start with at least 4 hex digits.
Humans are smarter than programs, ignore spurious lines.
The original ksymoops.cc was written by Greg McGary
<gkm@magilla.cichlid.com> and updated by Andreas Schwab
<schwab@issan.informatik.uni-dortmund.de>. That version required C++
and supported only ix86 and m68k.
To get the equivalent of the old ksymoops.cc (no vmlinux, no modules,
no ksyms, no System.map) use ksymoops -VKLOM. Or to just read
System.map, ksymoops -VKLO -m mapfile.
