[Beowulf] Strange "resume" statements generated for GRUB2

Mikhail Kuzminsky mikky_m at mail.ru
Mon Jun 10 10:20:05 PDT 2013


  Skylar Thompson <skylar.thompson at gmail.com> wrote:

>Hibernation isn't strictly suspension - it's writing all allocated,
>non-file-backed portions of memory to the paging/swap space. When the
>system comes out of hibernation, it boots normally and then looks for a
>hibernation image in the paging space. If it finds one, it loads that
>back into system memory rather than proceeding with a regular boot. This
>is in contract to system suspension, which depends on hardware support
>to place CPU, memory, and other system devices into a low power state,
>and wait for a signal to power things back up, bypassing the boot process.

Taking into account small size of my swap partition (4GB only), less than my RAM size,
(I wrote about this situation in my 1st message) the hibernation image may not fit into swap partition. Therefore coding of -part2 (for /) in resume statement is preferred (right for general case).    

>I'm not a SuSE expert so I'm not sure what YaST is doing, but I imagine
>you have to make grub changes via YaST rather than editing the grub
>configs directly.
>Skylar
Generally speaking, you are right. But I myself strongly prefer to know what occurs at linux level - to have the "natural" possibility (enough knowledge) to work w/OpenSUSE, Fedora etc.  
So I prefer to change GRUB2 configuration files :-)

Mikhail

>>On 06/09/2013 11:37 AM, Mikhail Kuzminsky wrote:
> >I have swap in sda1 and "/" in sda2 partitions of HDD. At installation
> >of OpenSUSE 12.3 (where YaST2 is used) on my cluster node I found
> >erroneous, by my opinion, boot loader (GRUB2) settings.
>>
> >YaST2 proposed (at installation) to use
> >... resume=/dev/disk/by-id/ata-WDC-... -part1 splash=silent ...
>>
> >in configuration of GRUB2. This parameters are transmitted (at linux
> >loading) by GRUB2 to linux kernel. GRUB2 itself, according my
> >installation settings, was installed to MBR. I changed (at installation
> >stage) -part1 to -part2, but after that YaST2 restored it back to -
> >part1 value !
> >And after installation OpenSuSE boots successfully !
> >I found (in installed OpenSuSE) 2 GRUB2 configuration files w/erroneous
>> -part1 setting.
>>
> >I found possible interpretation of this behaviour in /var/log/messages.
> >I found in this file the strings:
> >[Kernel] PM: Checking hibernation image partition
> >/dev/disk/by-id/ata-WDC_...-part1
>>
> >[Kernel] PM: Hibernation Image partition 8:1 present
> >[Kernel] PM: Looking for hibernation image.
> >{Kernel] PM: Image not found (code -22)
> >[Kernel] PM: Hibernation Image partitions not present or could not be
loaded
>>
> >What does it means ? The hibernation image is writing to swap partition
> >? But I beleive that hibernation is really suppressed in my Linux
> >(cpufreq kernel modules are not loaded) , and my BIOS settings do not
> >allow any changes of CPU frequency. BTW, my swap partition is small (4
> >GB, but RAM size is 8 GB).
>>
> >Which GRUB2/resume settings are really right and why they are right ?


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