Re: [Crash-utility] question on some command params

Jun Koi wrote: > On Tue, Sep 23, 2008 at 12:49 AM, Dave Anderson <anderson(a)redhat.com&gt; > wrote: > >> Jun Koi wrote: >> >>> Hi, >>> >>> I found below cmdline params having no documentation anywhere, so >>> could somebody explain their meaning? >>> >>> - memory_module >>> - no_modules >>> - no_ikconfig >>> - no_namelist_gzip >>> - no_kmem_cache >>> - kmem_cache_delay >>> - readnow >>> - buildinfo >>> - zero_excluded >>> >>> >>> Many thanks, >>> J >> >> >> They're all essentially debug flags for use on kernels/dumpfiles >> that for some reason or other would not initialize properly. >> >> memory_module: if /dev/mem or /dev/crash do not suffice you could >> force-feed one or the other for live system analysys. > > > > Another question: Why do we need the "memory_device" param if we > already had "memory_module"? Arent they the same thing? The naming > here is so confused to me. No. pc->memory_module is the truncated name of a loadable module, if one is necessary, consisting of the module object file name minus the ".o" or ".ko", whichever is applicable. /dev/mem does not require a pre-installed kernel module, whereas /dev/crash requires the crash.o or crash.ko misc driver to be installed. So if by chance you want to use your own hand-rolled memory device, it may or may not require that a kernel module be installed. If it does, then you would put "--memory_module your-memory-module.ko" on the command line. pc->memory_device is the name of a device file, i.e., "/dev/mem" or "/dev/crash". It is initialized to "/dev/crash" in hopes that it exists, and defaults to "/dev/mem" if it doesn't. But again, if you have your own memory device you'd like to use, you can override both of them by putting "--memory_module /dev/whatever" on the command

line. More important is pc->live_memsrc, which is the name of the live memory source that is actually used. The get_live_memory_source() is the arbitrator function that initializes pc->live_memsrc based upon: 1. the system contents (does the crash.[o|ko] module exist?), and 2. any user overrides using the --memory_module and --memory_device command line arguments.