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Thread: dmesg explained

  1. #1
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    dmesg explained

    Hello,

    Taking the following dmesg excerpt from my system, I would like to know a bit more about the marked coloured parts:

    [ 1.614145] ehci_hcd 0000:00:1d.7: irq 23, io mem 0x40104000
    [ 1.628728] r8169 0000:05:00.0: eth0: RTL8102e at 0xf8228000, 00:03:0d:fd:64:b1, XID 04e00000 IRQ 43
    [ 1.660074] ehci_hcd 0000:00:1d.7: USB 2.0 started, EHCI 1.00

    Red=???

    Green=???

    Blue=blue section is the start memory interval a specific hardware device occupies in the system's RAM memory map. Correct if I'm wrong though...

    Pink=pink section is the LAN MAC address. Correct if I'm wrong though...

    Orange=???

    Ah... one other thing:
    In what conditions can the RED, GREEN and BLUE values change?
    For example can they change if I reboot, or add a new hardware device?
    And if they can change, what controls that change? The kernel?

    Thank you
    Last edited by Binary-Synapse; June 9th, 2012 at 11:52 PM.
    Binary-Synapse

  2. #2
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    Re: dmesg explained

    Red is the time in seconds since the last re-boot or power up.

  3. #3
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    Re: dmesg explained

    Hi

    Red is the time stamp.

    Green looks to be the PCI bus ID.

    Blue is a memory address. Maybe the DMA address ? I don't believe it's the PCI configuration space address because of the values.

    As you say, pink is the lan card MAC address.

    I'm unsure about orange. Maybe it's a firmware ID or a chipset ID. I'm not sure.

    As for what changes when, i'm not totally sure without looking at the code or reading the PCI spec. I'm not going to do that tonight though

    Kind regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

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  4. #4
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    Re: dmesg explained

    Hello.


    Quote Originally Posted by Doug S View Post
    Red is the time in seconds since the last re-boot or power up.

    Using your information, I read a bit more, and indeed it is the time stamp.
    It's not in human readable format though...

    Thanks.
    Last edited by Binary-Synapse; June 10th, 2012 at 09:00 PM.
    Binary-Synapse

  5. #5
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    Re: dmesg explained

    Quote Originally Posted by matt_symes View Post
    Hi

    Blue is a memory address. Maybe the DMA address ? I don't believe it's the PCI configuration space address because of the values.

    I'm unsure about orange. Maybe it's a firmware ID or a chipset ID. I'm not sure.

    As for what changes when, i'm not totally sure without looking at the code or reading the PCI spec. I'm not going to do that tonight though

    Kind regards
    So blue is not the start of a dedicated portion of RAM space for hardware usage?

    Thank you.
    Binary-Synapse

  6. #6
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    Re: dmesg explained

    I believe [1.660074] means just 1.660074 seconds. It doesn't get much more
    human-readable than that.

  7. #7
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    Re: dmesg explained

    Hi

    So blue is not the start of a dedicated portion of RAM space for hardware usage?
    The blue is a dedicated portion of memory for the device. I'm just not sure what that memory is dedicated for.

    I will be reading through the PCI spec at some point soon and then i will be able to tell you.

    Maybe this will hold some clues for you.

    http://www.xml.com/ldd/chapter/book/ch15.html

    Kind regards
    Last edited by matt_symes; June 10th, 2012 at 09:27 PM.
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

    Thinking about becoming an Ubuntu Member?

  8. #8
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    Re: dmesg explained

    Quote Originally Posted by kreemoweet View Post
    I believe [1.660074] means just 1.660074 seconds. It doesn't get much more
    human-readable than that.
    Yes you are right.

    But what I meant was: instead of the format seconds.microseconds, it would be better if it was in the ISO8601 format.
    Something like 2012-06-09 21:30:00.

    Because otherwise it only serves as a time counter starting from the boot moment (which is still usefull)... but you will have to perform some time calculations if you need to know for example at what time/date a specific error (trapped by dmesg) really ocurred.

    But nevermind... I found what I was looking for:
    cat /var/log/kern.log

    The command above, will print both the normal dmesg time stamps AND ALSO the ISO8601 time stamp.
    And in my system dmesg -T doesn't work.

    Thank you.
    Last edited by Binary-Synapse; June 11th, 2012 at 02:42 AM.
    Binary-Synapse

  9. #9
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    Re: dmesg explained

    Quote Originally Posted by matt_symes View Post
    Hi

    The blue is a dedicated portion of memory for the device. I'm just not sure what that memory is dedicated for.

    I will be reading through the PCI spec at some point soon and then i will be able to tell you.

    Maybe this will hold some clues for you.

    http://www.xml.com/ldd/chapter/book/ch15.html

    Kind regards
    Thank you Matt.

    I would appreciate if you could provide me more insight on that matter (when you have the time).

    And also... thank you for the provided URL.
    Binary-Synapse

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