"writing `/dev/mem': Bad address" Error writing to ACPI area with 32 bit kernel
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Invalid
|
Medium
|
Unassigned |
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-
ProcVersionSign
Uname: Linux 3.5.0-10-generic i686
ApportVersion: 2.4-0ubuntu6
Architecture: i386
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/
Date: Wed Aug 15 13:42:37 2012
HibernationDevice: RESUME=
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha i386 (20120730.1)
MachineType: CLEVO CO. W240EU/
ProcEnviron:
LANGUAGE=en_GB:en
TERM=xterm
PATH=(custom, user)
LANG=en_GB.UTF-8
SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=
RelatedPackageV
linux-
linux-
linux-firmware 1.88
RfKill:
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.
dmi.board.name: W240EU/
dmi.board.vendor: CLEVO CO.
dmi.board.version: V3.0
dmi.chassis.
dmi.chassis.type: 10
dmi.chassis.vendor: No Enclosure
dmi.chassis.
dmi.modalias: dmi:bvnAmerican
dmi.product.name: W240EU/
dmi.product.
dmi.sys.vendor: CLEVO CO.
Changed in linux (Ubuntu): | |
status: | New → Confirmed |
Would it be possible for you to test the latest upstream kernel? Refer to https:/ /wiki.ubuntu. com/KernelMainl ineBuilds . Please test the latest v3.5kernel[0] (Not a kernel in the daily directory) and install both the linux-image and linux-image-extra .deb packages.
Once you've tested the upstream kernel, please remove the 'needs- upstream- testing' tag. Please only remove that one tag and leave the other tags. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs- upstream- testing' text.
If this bug is fixed in the mainline kernel, please add the following tag 'kernel- fixed-upstream' .
If the mainline kernel does not fix this bug, please add the tag: 'kernel- bug-exists- upstream' .
If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel- unable- to-test- upstream' .
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".
Thanks in advance.
[0] http:// kernel. ubuntu. com/~kernel- ppa/mainline/ v3.6-rc1- quantal/