[lkml]   [2005]   [Mar]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Subject[RFC] Obtaining memory information for kexec/kdump

    The topic of creating a common interface across
    architectures for obtaining system RAM information has been
    discussed on lkml and fastboot for a while now. Kexec needs
    information about the entire physical RAM present in the
    system while kdump needs information on the memory that the
    kernel has booted with.

    The /proc/iomem interface is insufficient because its
    behavior varies across architectures.

    - on i386, /proc/iomem reflects the memory that the system
    has booted with. But, it does not reflect memory above 4GB.
    - on x86_64, /proc/iomem reflects the entire physical memory
    present irrespective of how much memory the kernel has
    booted with.
    - on ppc64, /proc/iomem does not reflect system RAM at all.

    The patches that follow provide two views in the proc file
    system so we have a common mechanism of extracting this

    - A map of the entire physical memory present, irrespective
    of whether the system has been booted with mem= or memmap=
    options. This view comes up as /proc/physmem.

    - A map of the memory currently used by the kernel. This map
    can be accessed as /proc/activemem. This view will vary from
    the previous one depending upon the values provided by mem=
    or memmap= options.

    Since the patches made use of the "resource" struct to store
    and retrieve this information, some modifications were
    needed to convert the "start" and "end" fields of struct
    resource to u64. The first patch of the series makes this
    conversion. The rest of the patches provide the code for the
    two maps.

    The patches are for the i386 and x86_64 architectures and
    against 2.6.12-rc1-mm1.

    Kindly review and comment on the patches.

    Thanks and Regards, Hari
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-04-06 13:30    [W:0.025 / U:70.212 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site