[Crash-utility] question on some command params

[Dave Anderson]

Dave Anderson wrote:
> Jun Koi wrote:
> 
>> On Tue, Sep 23, 2008 at 12:49 AM, Dave Anderson <anderson at redhat.com> 
>> 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

Sorry, I meant "--memory_device /dev/whatever" above...

> 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.
>