Using rEFInd to boot secondary OS whan primary OS is in deep sleep (hibernate)
An EFI boot manager utility
Status: Beta
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Hi all,
I own a Mac Pro 2010 that I'm using 99.999% of time running Mac OS X 10.6.8. I almost never reboot, until recently because I've installed Windows 7 on a dedicated drive.
Going back and forth between those two OSes is a pain.
I would like to put OS X in deep sleep (hibernation), and boot another OS, and go back on OS X after I'm done with the other OS.
I've googled a lot, made some tests of my own, but I can't make it happen.
Two questions:
I know that one of the purposes of rEFItBlesser was to prevent this behavior to happen, but my tests with rEFInd without rEFItBlesser are not successful.
rEFItBlesser did the following:
1) On startup, change the startup to Mac OS X instead of rEFIt. This is so that hibernate would boot back into Mac OS X properly.
2) On shutdown, change the startup to rEFIt instead of Mac OS X.
So, what rEFInd would have to do is have an option to restore OS X from hibernate.
First question: does rEFInd's current Mac OS X boot option not restore from hibernate?
If not, then second question: how does Mac OS X restore from hibernate? Maybe you can use the EFI Shell in rEFInd to compare nvram contents before a hibernate and after...
Anyway, it could be dangerous to run a different OS after a hibernate. The other OS could modify disk blocks that the hibernated OS has cached. Then the hibernated OS could cause disk corruption when it uses its cached disk blocks.
You could use a virtual machine in OS X to work with your Windows 7 partition (Parallels Desktop 9 is compatible with 10.6). Or you could use a newer version of OS X that will restart your apps when you login.
Thank you for your reply.
The thing is, it does not seem possible to bypass the wake-up from hibernate once you boot a Mac that was put in deep sleep. The alt key won't bring the regular screen that let you choose the boot drive. Neither it will show rEFInd menu. The Mac will go directly to a grey screen and restore your session from hibernation.
Some people (from few years old forum posts), using some non-identified Mac model appear to have successfully bypassed this restoration phase and booted on Windows. But it seems that going back on MacOS from here is a cold boot (like if you unplugged the power cord : session lost).
My guess is something (firmware?) is told to boot back to the hibernate state bypassing every other user available boot trick, but that info could be lost if you manage to boot something else in the mean time.
About your first question: I don't know, once I hibernate, I'm no longer able to get the rEFInd menu. But may be I should try harder. I've only tried to install rEFInd on dedicated EFI partition of various drives (got 5 in the Mac Pro).
Trying to get into EFI shell is a nice idea, but I'm not really EFI-proficient ;)
I know about the danger of modification of blocks but I'm not too concerned. The windows system does not see/use my HFS+ drives, son it should be ok.
The VM trick is not possible. I already own VMware Fusion, but performances are horrendous. I need full GPU power. I've tried to use ESXi as a barebone hypervisor, and create huge VMs using direct access hard drives and PCI-passthrough to the video card. It's working great on the GPU side, but sound would not work, and I was not able to dedicate a USB port to my VMs so I got no keyboard/mouse: unusable.
You can read more about this here: http://www.patpro.net/blog/index.php/2012/12/16/2319-mac-os-x-on-vmware-esxi-hardware-challenges/