kmem, snap: iomem/ioport display and vmcore snapshot support
----- Original Message -----
> From: Dave Anderson <email@example.com>
> Subject: Re: [Crash-utility] [PATCH] kmem, snap: iomem/ioport display
> and vmcore snapshot support
> Date: Tue, 13 Mar 2012 10:17:20 -0400 (EDT)
> > ----- Original Message -----
> >> Some days ago I was in a situation that I had to convert vmcore in
> >> kvmdump format into ELF since some extension module we have locally
> >> can be used only on relatively old crash utility, around version 4,
> >> but such old crash utility cannot handle kvmdump format.
> > That's a pretty weak argument -- what did crash version ~4 have
> > that the latest version does not? I don't recall ever removing
> > any functionality w/respect to extension module without replacing
> > it with a better interface. In other words, why can't you fix your
> > local extension module? I need a better reason for modifying
> > the snap module other than that.
> I don't know the detail of the local extension module. The man who
> requested a help to me explained that his module gets information of
> vmcore using crash (gdb) scripts and retrives values from the scripts'
> output via pipe. While old crash behaves well, recent ones appear to
> hang in the situation where both reading and writing sides wait each
> other. Is there any difference of behaviour on communication with
I don't know exactly. There's certainly have been new gdb versions,
and the changelog has a few small patches w/respect to gdb commands,
but it's hard to say how they might affect the usage of gdb scripts
from a module (?).
> Anyway it's natural that we should modify the extension module, and
> we'll do that soon. The patch for snap command was a workaround, but
> there's merit to the patch that it makes it possible to use it as
> handy vmcore conversion tool, not just as live kernel dump command, so
> I've posted this here. By this, snap command will become able to
> convert all the format currently crash supports into ELF. Though I
> have yet to test this, this can convert lkcd foramt into ELF, for
> example. Someone might want to use this for vmcore not suppoted by
OK, here's what to do. The snap extension module is just that -- it
takes a "snapshot" of live physical memory and creates an ELF file.
I don't want to change that.
However, I suppose the concept of a "conversion-to-ELF" tool makes sense.
That being the case, please create a standalone extension module, and
call it "mkelf", or "kvm2elf", or whatever name you want. Then we can
add it to the collection of modules on the extension module web page.
> > Why reinvent the wheel? The "dev -i" command does all of the above, plus
> > gives you the resource structure address:
> > crash> dev -i
> > RESOURCE RANGE NAME
> > ffffffff80312080 0000-ffff PCI IO
> I myself thought it's strange if it's not present. Before making my
> patch, I did minimum check by searching crash source code for related
> symbols such as ``resource', but I didn't find anything. Now I see
> some symbols found with the same keyword. I think I did something
> wrong at that time.
> HATAYAMA, Daisuke
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