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[Bug 1037094] Re: "writing `/dev/mem': Bad address" Error writing to ACPI area with 32 bit kernel


Christopher, this is no longer giving me a problem as bug 806032 has
been fixed.  However I have checked with Trusty (kernel 3.12.0-7 32 bit)
and the problem described here does still exist.  The bug is therefore
not invalid, but from my point of view it does not need fixing.  I don't
know what the convention is in such cases.  Won't Fix might be more
appropriate but it will not let me set it to that.

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  "writing `/dev/mem': Bad address" Error writing to ACPI area with 32
  bit kernel

Status in “linux” package in Ubuntu:

Bug description:
  Using the 32 bit kernel I am unable to write to the ACPI memory area
  using the command

  sudo dd if=value_file of=/dev/mem bs=1 seek=3660685688 count=4
  This gives the error
  dd: writing `/dev/mem': Bad address

  3660685688 is 0xDA31A178 and sudo cat /proc/iomem shows
  da216000-da32bfff : ACPI Non-volatile Storage

  This works ok with the 64 bit kernel.
  I have also tested it with the Oneiric kernel 3.0.0-12 and again the 64 bit kernel is ok but the 32 bit gives the error.

  In case it is relevant the context is that I am trying to apply the workaround for bug #806032 (
  Fn + F[89] does not work for controlling brightness on Clevo laptops) described in comment #7, which works perfectly on the 64 bit kernel but gives Bad Address error on 32 bit.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.10
  Package: linux-image-3.5.0-10-generic 3.5.0-10.10
  ProcVersionSignature: Ubuntu 3.5.0-10.10-generic 3.5.1
  Uname: Linux 3.5.0-10-generic i686
  ApportVersion: 2.4-0ubuntu6
  Architecture: i386
   /dev/snd/controlC0:  colinl     2142 F.... pulseaudio
  Date: Wed Aug 15 13:42:37 2012
  HibernationDevice: RESUME=UUID=386e4578-bf9d-4970-a10f-b0b513b32771
  InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha i386 (20120730.1)
  MachineType: CLEVO CO. W240EU/W250EUQ/W270EUQ
   PATH=(custom, user)
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-10-generic root=UUID=c5043680-f556-4f19-9e32-c6fdb4c05f9e ro quiet splash vt.handoff=7
   linux-restricted-modules-3.5.0-10-generic N/A
   linux-backports-modules-3.5.0-10-generic  N/A
   linux-firmware                            1.88
   0: phy0: Wireless LAN
   	Soft blocked: no
   	Hard blocked: yes
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 02/24/2012
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: 4.6.5
  dmi.board.asset.tag: Tag 12345
  dmi.board.name: W240EU/W250EUQ/W270EUQ
  dmi.board.vendor: CLEVO CO.
  dmi.board.version: V3.0
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: No Enclosure
  dmi.chassis.version: N/A
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr4.6.5:bd02/24/2012:svnCLEVOCO.:pnW240EU/W250EUQ/W270EUQ:pvrNotApplicable:rvnCLEVOCO.:rnW240EU/W250EUQ/W270EUQ:rvrV3.0:cvnNoEnclosure:ct10:cvrN/A:
  dmi.product.name: W240EU/W250EUQ/W270EUQ
  dmi.product.version: Not Applicable
  dmi.sys.vendor: CLEVO CO.

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