mod === :: NAME mod - module information and loading of symbols and debugging data SYNOPSIS mod -s module [objfile] | -d module | -S [directory] [-D|-t|-r|-R|-o|-g] DESCRIPTION With no arguments, this command displays basic information of the currently installed modules, consisting of the module address, name, base address, size, the object file name (if known), and whether the module was compiled with CONFIG_KALLSYMS. The arguments are concerned with with the loading or deleting of symbolic and debugging data from a module's object file. A modules's object file always contains symbolic data (symbol names and addresses), but contains debugging data only if the module was compiled with the -g CFLAG. In addition, the module may have compiled with CONFIG_KALLSYMS, which means that the module's symbolic data will have been loaded into the kernel's address space when it was installed. If the module was not compiled with CONFIG_KALLSYMS, then only the module's exported symbols will be loaded into the kernel's address space. Therefore, for the purpose of this command, it should noted that a kernel module may have been compiled in one of following manners: 1. If the module was built without CONFIG_KALLSYMS and without the -g CFLAG, then the loading of the module's additional non-exported symbols can be accomplished with this command. 2. If the module was built with CONFIG_KALLSYMS, but without the -g CFLAG, then there is no benefit in loading the symbols from the module object file, because all of the module's symbols will have been loaded into the kernel's address space when it was installed. 3. If the module was built with CONFIG_KALLSYMS and with the the -g CFLAG, then the loading of the module's debugging data can be accomplished with this command. 4. If the module was built without CONFIG_KALLSYMS but with the -g CFLAG, then the loading of the both module's symbolic and debugging data can be accomplished with this command. -s module [objfile] Loads symbolic and debugging data from the object file for the module specified. If no objfile argument is appended, a search will be made for an object file consisting of the module name with a .o or .ko suffix, starting at the /lib/modules/ directory on the host system, or if not found there, starting at the directory containing the kernel namelist file. If an objfile argument is appended, then that file will be used. -d module Deletes the symbolic and debugging data of the module specified. -S [directory] Load symbolic and debugging data from the object file for all loaded modules. For each module, a search will be made for an object file consisting of the module name with a .o or .ko suffix, starting at the /lib/modules/ directory of the host system, or if not found there, starting at the directory containing the kernel namelist file. If a directory argument is appended, then the search will be restricted to that directory. -D Deletes the symbolic and debugging data of all modules. -t Display the contents of the module's "taints" bitmask if it is non-zero. When possible, the "taints" bits are translated to symbolic letters of the taint type; otherwise the hexadecimal value is shown. In older kernels, the contents of the "license_gplok" field is displayed in hexadecimal; the field may be either a bitmask or a boolean, depending upon the kernel version. The relevant kernel sources should be consulted for the meaning of the letter(s) or hexadecimal bit value(s). For modules that have a "gpgsig_ok" field that is zero (unsigned), the notation "(U)" is shown. -r Passes the -readnow flag to the embedded gdb module, which will override the two-stage strategy that it uses for reading symbol tables from module object files. -R Reinitialize module data. All currently-loaded symbolic and debugging data will be deleted, and the installed module list will be updated (live system only). -g When used with -s or -S, add a module object's section start and end addresses to its symbol list. -o Load module symbols with old mechanism. If the crash session was invoked with the "--mod " option, or a CRASH_MODULE_PATH environment variable exists, then /lib/modules/ will be overridden as the default directory tree that is searched for module object files. After symbolic and debugging data have been loaded, backtraces and text disassembly will be displayed appropriately. Depending upon the processor architecture, data may also printed symbolically with the "p" command; at a minimum, the "rd" command may be used with module data symbols. If crash can recognize that the set of modules has changed while running a session on a live kernel, the module data will be reinitialized the next time this command is run; the -r option forces the reinitialization. EXAMPLES Display the currently-installed modules: crash> mod MODULE NAME BASE SIZE OBJECT FILE f7e44c20 dm_mod f7e34000 88568 (not loaded) f7e5a8a0 dm_log f7e59000 8354 (not loaded) f7e66420 dm_region_hash f7e65000 9708 (not loaded) f7e76b60 dm_mirror f7e74000 12609 (not loaded) f7e8b8e0 ata_piix f7e87000 20637 (not loaded) ... Display the currently-installed modules on a system where all modules were compiled with CONFIG_KALLSYMS: crash> mod MODULE NAME BASE SIZE OBJECT FILE f7e44c20 dm_mod f7e34000 88568 (not loaded) [CONFIG_KALLSYMS] f7e5a8a0 dm_log f7e59000 8354 (not loaded) [CONFIG_KALLSYMS] f7e66420 dm_region_hash f7e65000 9708 (not loaded) [CONFIG_KALLSYMS] f7e76b60 dm_mirror f7e74000 12609 (not loaded) [CONFIG_KALLSYMS] f7e8b8e0 ata_piix f7e87000 20637 (not loaded) [CONFIG_KALLSYMS] ... Load the symbolic and debugging data of all modules: crash> mod -S MODULE NAME BASE SIZE OBJECT FILE f7e44c20 dm_mod f7e34000 88568 /lib/modules/2.6.32/kernel/drivers/md/dm-mod.ko f7e5a8a0 dm_log f7e59000 8354 /lib/modules/2.6.32/kernel/drivers/md/dm-log.ko f7e66420 dm_region_hash f7e65000 9708 /lib/modules/2.6.32/kernel/drivers/md/dm-region-hash.ko f7e76b60 dm_mirror f7e74000 12609 /lib/modules/2.6.32/kernel/drivers/md/dm-mirror.ko f7e8b8e0 ata_piix f7e87000 20637 /lib/modules/2.6.32/kernel/drivers/ata/ata_piix.ko ... Load the symbolic and debugging data of the dm_mod module from its known location: crash> mod -s dm_mod MODULE NAME BASE SIZE OBJECT FILE f7e44c20 dm_mod f7e34000 88568 /lib/modules/2.6.32/kernel/drivers/md/dm-mod.ko Delete the current symbolic and debugging data of the dm_mod module, and then re-load it from a specified object file: crash> mod -d dm_mod crash> mod -s dm_mod /tmp/dm_mod.ko MODULE NAME BASE SIZE OBJECT FILE f7e44c20 dm_mod f7e34000 88568 /tmp/dm-mod.ko After installing a new kernel module on a live system, reinitialize the installed module list: crash> !modprobe soundcore crash> mod mod: NOTE: modules have changed on this system -- reinitializing MODULE NAME BASE SIZE OBJECT FILE f7e44c20 dm_mod f7e34000 88568 (not loaded) f7e5a8a0 dm_log f7e59000 8354 (not loaded) f7e62e40 soundcore f7e62000 6390 (not loaded) f7e66420 dm_region_hash f7e65000 9708 (not loaded) f7e76b60 dm_mirror f7e74000 12609 (not loaded) f7e8b8e0 ata_piix f7e87000 20637 (not loaded) ... Display modules that are "tainted", where in this case where they are proprietary and unsigned: crash> mod -t NAME TAINT vxspec P(U) vxportal P(U) fdd P(U) vxfs P(U) vxdmp P(U) vxio P(U) vxglm P(U) vxgms P(U) vxodm P(U)