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> 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.
Dave