[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. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
Colin Law, thank you for your comments. As outlined in https://wiki.ubuntu.com/Bugs/Status Won't Fix would be more appropriate, for example, if you desired the outcome noted in the Bug Description, and the maintainers didn't want to implement it on technical grounds. Given you are no longer interested in this being fixed, it's considered Invalid. However, if you change your mind in the future, this report could always be reopened, and resumed where it was left off. Thank you for reporting this and helping make Ubuntu better. Please feel free to report any future bugs you may find. ** Changed in: linux (Ubuntu) Status: Incomplete = Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
Colin Law, given bug 806032 is resolved for you, would you need anyone to look into this, or may this be closed as Status Invalid? ** Changed in: linux (Ubuntu) Status: Confirmed = Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
This issue appears to be an upstream bug, since you tested the latest upstream kernel. Would it be possible for you to open an upstream bug report[0]? That will allow the upstream Developers to examine the issue, and may provide a quicker resolution to the bug. If you are comfortable with opening a bug upstream, It would be great if you can report back the upstream bug number in this bug report. That will allow us to link this bug to the upstream report. [0] https://wiki.ubuntu.com/Bugs/Upstream/kernel -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
Joseph, having looked at the link for reporting upstream, the first thing I have to do is to identifier the maintainer from [1] and email a report to him. However I have no idea how to find the right maintainer for this problem from the massive list. Can you help? [1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=MAINTAINERS -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
Joseph, you have asked me to try the latest 3.5 kernel, but the link is to 3.6 rc1. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
Joseph, you have asked me to try the latest 3.5 kernel, but the link is to 3.6 rc1, but I have assumed that it is the 3.6 that is required. Tested against 3.6.0-030600rc1-generic_3.6.0-030600rc1.201208022056_i386, problem still seen. ** Tags removed: needs-upstream-testing ** Tags added: kernel-bug-exists-upstream ** Changed in: linux (Ubuntu) Status: Incomplete = Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
When I tested it, it also applies for reading.
sudo dd if=/dev/mem bs=1 count=1 skip=$ADDR
This was a 32-bit Ubuntu 12.04 Live CD on a 64-bit desktop machine. ADDR
is any address higher than or equal to 0xf7bfe000 (see below).
Using strace and writing a minimalistic C program, I could verify that
open() and _llseek() works, but that read() fails with -EFAULT.
From the static read_mem function in drivers/char/mem.c at
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/char/mem.c;h=e5eedfa24c91010bd8358db7b7076e4f0af6ad1b;hb=HEAD#l96
there are three places where -EFAULT could be returned. But when using read(fd,
buffer, 0), only the below is supposed to give issues:
103 if (!valid_phys_addr_range(p, count))
104 return -EFAULT;
Since ARCH_HAS_VALID_PHYS_ADDR_RANGE is not set for x86, valid_phys_addr_range
is:
49 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
50 {
51 return addr + count = __pa(high_memory);
52 }
A simple module that includes linux/mm.h can read the values from memory:
high_memory is a void pointer to 0xf7bfe000
__pa(high_memory) is an unsigned long that contains 0x37bfe000
Obviously, the ASL address that we are trying to read is highjer than that and
thus the read fails with -EFAULT.
http://lxr.free-electrons.com/source/arch/x86/include/asm/page.h#L36
36 #define __pa(x) __phys_addr((unsigned long)(x))
http://lxr.free-electrons.com/source/arch/x86/mm/physaddr.c#L11
basically x - PAGE_OFFSET
Since the CONFIG_X86_64 is not set, the file that is included by page_types.h:
http://lxr.free-electrons.com/source/arch/x86/include/asm/page_32_types.h#L16
#define __PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
.config (or /boot/config-...) contains CONFIG_PAGE_OFFSET=0xC000
which is exactly the difference above.
So far the analysis. I don't know if there is a solution available for
/dev/mem.
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writing `/dev/mem': Bad address Error writing to ACPI area with 32
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[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
** Changed in: linux (Ubuntu) Status: New = Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1037094] Re: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel
Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . 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/ ** Tags added: needs-upstream-testing ** Changed in: linux (Ubuntu) Importance: Undecided = Medium ** Changed in: linux (Ubuntu) Status: Confirmed = Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037094 Title: writing `/dev/mem': Bad address Error writing to ACPI area with 32 bit kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1037094/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
