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    SubjectRe: [RFC] Obtaining memory information for kexec/kdump
    Dave Hansen wrote:
    > On Thu, 2005-03-24 at 11:19 +0530, Hariprasad Nellitheertha wrote:
    >
    ...

    > I think there's likely a lot of commonality with the needs of memory
    > hotplug systems here. We effectively dump out the physical layout of
    > the system, but in sysfs. We do this mostly because any memory hotplug
    > changes generate hotplug events, just like all other hardware. If you
    > do this in /proc, it's another thing that memory hotplug will have to
    > update.

    We put it in /proc primarily because what we wanted was
    similar in many ways to /proc/iomem and so we (re)use a bit
    of the code. Also, we were wondering if it is appropriate to
    put in multiple values in a single file in sysfs.

    >
    > Also, we already have a concept of active and non-active physical
    > memory: we call it online and offline. Some tweaks to the information
    > that we export might be all that you need, instead of creating a new
    > interface.

    Looks like. And the tweaks could be handled by the user
    space kexec-tools.

    I've attached a document I started writing a couple days ago
    > about the sysfs layout and the call paths for hotplug. It's horribly
    > incomplete, but not a bad start.
    >
    > If you want to see some more details of the layout, please check out
    > this patch set:
    >
    > http://www.sr71.net/patches/2.6.12/2.6.12-rc1-mhp1/patch-2.6.12-rc1-mhp1.gz

    This does not have the sysfs related code. Is there a
    separate patch for adding the sysfs entries?

    >
    > A good example of all of the hotplug stuff enabled for a normal machine
    > is this .config, it boots on my 4-way PIII Xeon.
    >
    > http://www.sr71.net/patches/2.6.12/2.6.12-rc1-mhp1/configs/config-i386-sparse-hotplug
    >
    > You're welcome to borrow the machine that I normally boot this config
    > on. Should make booting it relatively foolproof. :)
    >
    > -- Dave
    >
    >
    > ------------------------------------------------------------------------
    >
    > block_size_bytes: The size of each memory section (in hex)

    This value is per memoryXXXX directory, right?


    Regards, Hari
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