Vraag & Antwoord

OS Linux

Echt leuk :)

5 antwoorden
  • Steve Ballmer maakt tegenwoordig ook muziek. En nog goede ook.


    Meer clips van onze Steve vind je hier:

  • Alleen leuk voor de anti-microsoft-fans. Niks specifieks voor op een linux-forum, volgens mij. Maar ik snap verder wel dat je het hier plaatst :wink:
  • Niks anti-microsoft zie bijv. mijn avatar :wink:. De shows van Stevie zijn gewoon leuk. Mogen de linux mensen ook eens genieten. Meneer Ballmer laat ons kosteloos lachen. Echt top van hem :D.

    /me gaat binnenkort een Steve Ballmer fanclub oprichten 8)
  • Zit ik laatst een niewue kernel (2.6.10-rc1) te configureren, kom ik softsuspend tegen. Toevallig had ik ook per ongeluk ACPI weer ingeschakeld (deed het niet met vroege 2.6-kernels). ACPI blijkt het weer prima te doen, dus ook eens softwaresuspend uit proberen. En het werkt gewoon :D . Eerlijkheid gebied dat ik het nog slechts een keer heb geprobeerd, maar het is toch leuk voor een pc, die richting een leeftijd van 5 jaar gaat (P3-500).

    Een en ander is nog wel in de experimentele fase, dus voorlopig unmount ik maar even /home. De optie in de kernel is te vinden bij:

    Power management options > Power Management suport > Software Suspend

    Het zou zelfs moeten werken met APM

    Hieronder de tekst uit de kernel documentatie.


    From kernel/suspend.c:

    * BIG FAT WARNING *********************************************************
    * If you have unsupported (*) devices using DMA…
    * …say goodbye to your data.
    * If you touch anything on disk between suspend and resume…
    * …kiss your data goodbye.
    * If your disk driver does not support suspend… (IDE does)
    * …you'd better find out how to get along
    * without your data.
    * If you change kernel command line between suspend and resume…
    * …prepare for nasty fsck or worse.
    * (*) suspend/resume support is needed to make it safe.

    You need to append resume=/dev/your_swap_partition to kernel command
    line. Then you suspend by

    echo shutdown > /sys/power/disk; echo disk > /sys/power/state

    . If you feel ACPI works pretty well on your system, you might try

    echo platform > /sys/power/disk; echo disk > /sys/power/state

    Article about goals and implementation of Software Suspend for Linux
    Author: G‚ábor Kuti
    Last revised: 2003-10-20 by Pavel Machek

    Idea and goals to achieve

    Nowadays it is common in several laptops that they have a suspend button. It
    saves the state of the machine to a filesystem or to a partition and switches
    to standby mode. Later resuming the machine the saved state is loaded back to
    ram and the machine can continue its work. It has two real benefits. First we
    save ourselves the time machine goes down and later boots up, energy costs
    are real high when running from batteries. The other gain is that we don't have to
    interrupt our programs so processes that are calculating something for a long
    time shouldn't need to be written interruptible.

    swsusp saves the state of the machine into active swaps and then reboots or
    powerdowns. You must explicitly specify the swap partition to resume from with
    ``resume='' kernel option. If signature is found it loads and restores saved
    state. If the option ``noresume'' is specified as a boot parameter, it skips
    the resuming.

    In the meantime while the system is suspended you should not add/remove any
    of the hardware, write to the filesystems, etc.

    Sleep states summary

    There are three different interfaces you can use, /proc/acpi should
    work like this:

    In a really perfect world:
    echo 1 > /proc/acpi/sleep # for standby
    echo 2 > /proc/acpi/sleep # for suspend to ram
    echo 3 > /proc/acpi/sleep # for suspend to ram, but with more power conservative
    echo 4 > /proc/acpi/sleep # for suspend to disk
    echo 5 > /proc/acpi/sleep # for shutdown unfriendly the system

    and perhaps
    echo 4b > /proc/acpi/sleep # for suspend to disk via s4bios

    Frequently Asked Questions

    Q: well, suspending a server is IMHO a really stupid thing,
    but… (Diego Zuccato):

    A: You bought new UPS for your server. How do you install it without
    bringing machine down? Suspend to disk, rearrange power cables,

    You have your server on UPS. Power died, and UPS is indicating 30
    seconds to failure. What do you do? Suspend to disk.

    Ethernet card in your server died. You want to replace it. Your
    server is not hotplug capable. What do you do? Suspend to disk,
    replace ethernet card, resume. If you are fast your users will not
    even see broken connections.

    Q: Maybe I'm missing something, but why don't the regular I/O paths work?

    A: We do use the regular I/O paths. However we cannot restore the data
    to its original location as we load it. That would create an
    inconsistent kernel state which would certainly result in an oops.
    Instead, we load the image into unused memory and then atomically copy
    it back to it original location. This implies, of course, a maximum
    image size of half the amount of memory.

    There are two solutions to this:

    * require half of memory to be free during suspend. That way you can
    read "new" data onto free spots, then cli and copy

    * assume we had special "polling" ide driver that only uses memory
    between 0-640KB. That way, I'd have to make sure that 0-640KB is free
    during suspending, but otherwise it would work…

    suspend2 shares this fundamental limitation, but does not include user
    data and disk caches into "used memory" by saving them in
    advance. That means that the limitation goes away in practice.

    Q: Does linux support ACPI S4?

    A: Yes. That's what echo platform > /sys/power/disk does.

    Q: My machine doesn't work with ACPI. How can I use swsusp than ?

    A: Do a reboot() syscall with right parameters. Warning: glibc gets in
    its way, so check with strace:

    reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, 0xd000fce2)

    (Thanks to Peter Osterlund:)

    #include <unistd.h>
    #include <syscall.h>

    #define LINUX_REBOOT_MAGIC1 0xfee1dead
    #define LINUX_REBOOT_MAGIC2 672274793

    int main()
    return 0;

    Also /sys/ interface should be still present.

    Q: What is 'suspend2'?

    A: suspend2 is 'Software Suspend 2', a forked implementation of
    suspend-to-disk which is available as separate patches for 2.4 and 2.6
    kernels from swsusp.sourceforge.net. It includes support for SMP, 4GB
    highmem and preemption. It also has a extensible architecture that
    allows for arbitrary transformations on the image (compression,
    encryption) and arbitrary backends for writing the image (eg to swap
    or an NFS share[Work In Progress]). Questions regarding suspend2
    should be sent to the mailing list available through the suspend2
    website, and not to the Linux Kernel Mailing List. We are working
    toward merging suspend2 into the mainline kernel.

    Q: A kernel thread must voluntarily freeze itself (call 'refrigerator').
    I found some kernel threads that don't do it, and they don't freeze
    so the system can't sleep. Is this a known behavior?

    A: All such kernel threads need to be fixed, one by one. Select the
    place where the thread is safe to be frozen (no kernel semaphores
    should be held at that point and it must be safe to sleep there), and

    if (current->flags & PF_FREEZE)

    If the thread is needed for writing the image to storage, you should
    instead set the PF_NOFREEZE process flag when creating the thread.

    Q: What is the difference between between "platform", "shutdown" and
    "firmware" in /sys/power/disk?


    shutdown: save state in linux, then tell bios to powerdown

    platform: save state in linux, then tell bios to powerdown and blink
    "suspended led"

    firmware: tell bios to save state itself [needs BIOS-specific suspend
    partition, and has very little to do with swsusp]

    "platform" is actually right thing to do, but "shutdown" is most



    Veel plezier voor de knutselaars. :D :D
  • zucht

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