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Is swap space endian-sensitive?

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  • Mike (mwester)
    Hey kernel experts - is the swap partition supposed to be endian-sensitive? See the log exerpt below, 4th line (the swap space was mkswap d on SlugOS/LE, this
    Message 1 of 2 , Jan 1 9:14 PM
      Hey kernel experts - is the swap partition supposed to be endian-sensitive?
      See the log exerpt below, 4th line (the swap space was "mkswap"d on
      SlugOS/LE, this is from a SlugOS/BE kernel -- clearly it doesn't like the
      magic number for the swap...) -- is this a bug (in which case I'll try to
      fix it) or is this a feature?
      Thanks!

      kjournald starting. Commit interval 5 seconds
      EXT3 FS on sda2, internal journal
      EXT3-fs: mounted filesystem with ordered data mode.
      Unable to handle swap header version 16777216
      Starting syslogd/klogd: done
      Configuring update-modules
    • John Reiser
      ... It s an endian-sensitive performance issue. A swap partition is not just a big blob of disk space with a label. A persistent on-disk data structure
      Message 2 of 2 , Jan 2 7:41 AM
        > Hey kernel experts - is the swap partition supposed to be endian-sensitive?
        > (the swap space was "mkswap"d on SlugOS/LE, this is from a SlugOS/BE kernel)

        > "Unable to handle swap header version 16777216"

        It's an endian-sensitive performance issue. A swap partition is not just
        a big blob of disk space with a label. A persistent on-disk data structure
        allows for avoiding the use of bad blocks, etc., and there is a cost in
        code space and complexity for making the storage and access endian-ambivalent.
        For modern desktop and server machines the cost might be trivial, but for
        embedded use everything matters. The workaround to allow for changing
        endianness is to mkswap [just] before swapon, and you must be sure to perform
        the mkswap with correct parameters.

        --
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