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[GUIDE] Patching the kernel for Haswell CPUs, XCPM early reboot


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I am having some sleep problems with my Z97N-Gaming 5/i5-4460/HD4600 system.

 

Just to clarify. For a CPU like mine (Haswell refresh):

- The xcpm flag is NOT needed.

- The KernelPm option IS needed.

 

Is this correct? I've tried a mixture of setting, but so far nothing has solved the problem. I can sleep/wake several times, but sometimes after longer periods of sleep, the machine wakes, then reboots, with no kernel panic (it seems so at least). I'm unsure what to do from here, but I'm sure it has to do with power management.

  • 2 weeks later...

path 10.10.2 ? Step by step be welcome.

Post #1.

I am having some sleep problems with my Z97N-Gaming 5/i5-4460/HD4600 system.

 

Just to clarify. For a CPU like mine (Haswell refresh):

- The xcpm flag is NOT needed.

- The KernelPm option IS needed.

 

Is this correct? I've tried a mixture of setting, but so far nothing has solved the problem. I can sleep/wake several times, but sometimes after longer periods of sleep, the machine wakes, then reboots, with no kernel panic (it seems so at least). I'm unsure what to do from here, but I'm sure it has to do with power management.

XCPM is default for Haswell CPUs.

KernelPm is needed if your BIOS locks MSR 0xE2.

  • Like 1
  • 4 weeks later...
  • 2 weeks later...

Hi Rehabman,

 

How about the patch for Ivybridge CPU? I would like to use -XCPM flag for my ivybridge CPU (3230M), but I am not clear about the usefulness of this patch for ivybridge CPU. Now, my laptop works smoothly without this -XCPM flag, but sometimes it can not wake from sleep (black screen on waking). Do you have any advise for me? Thanks so much

Hi Rehabman,

 

How about the patch for Ivybridge CPU? I would like to use -XCPM flag for my ivybridge CPU (3230M), but I am not clear about the usefulness of this patch for ivybridge CPU. Now, my laptop works smoothly without this -XCPM flag, but sometimes it can not wake from sleep (black screen on waking). Do you have any advise for me? Thanks so much

It is -xcpm, not -XCPM.

 

Same patch.

 

Your sleep problem is likely something else.

Thanks Rehabman, so what is the benefit for using -xcpm flag for ivybridge CPU?

Not sure any benefit has been quantified. It will cause the system to use XCPM in the kernel for CPU power management instead of AppleIntelCPUPowerManagement.kext. In some cases (MacBookAir5,x with Core i3, for example) it can simplify getting CPU PM to work (MacBookAir seems to be picky about non-Apple CPUs).

 

But Apple's own machines do not use XCPM for Ivy (by default), so it is somewhat unclear as to why the support is even there in the first place.

  • Like 1

Not sure any benefit has been quantified. It will cause the system to use XCPM in the kernel for CPU power management instead of AppleIntelCPUPowerManagement.kext. In some cases (MacBookAir5,x with Core i3, for example) it can simplify getting CPU PM to work (MacBookAir seems to be picky about non-Apple CPUs).

 

But Apple's own machines do not use XCPM for Ivy (by default), so it is somewhat unclear as to why the support is even there in the first place.

I am clear now. Thanks Rehabman. Have a nice day.

  • Like 1
  • 3 months later...

Hello

 

I CANT FIND THE KERNEL IN THE USB INSTALLER at the location you specified

How did you create your USB installer?

 

What version of OS X? This guide is for Yosemite.

@RehabMan i created the yosemite usb using the disk utility restore method.(base system.dmg)

I believe kernel has to be manually extracted, copied.

 

Note: You should consider using Clover. Legacy bootloaders with modern hardware somewhat silly...

  • 2 months later...

Hi guys, I've read all info here, but... I have Xeon E3-1241 v3 which is Haswell. I've run my system with not patched kernel, generate SSDT using ssdtPRGen. I've also tried your kernel patch, Clover "-xcpm" and "kernelPM" options, but all I get is the same working system but without C-states. I've got only 8 and 35 + 4 turbo states. My system sleeps well, wakes well without problem. With or without patched kernel, with SSDT.aml or without, tried iMac14,2 and MacPro6,1 smbios, result is all the time the same, no extra c-states, just the above two (8 and 35). I have no idea what am I to do more to get c-states working. 

  • 10 months later...

RehabMan,

Do you know if you XCPM should be used for Broadwell-E?  I tried enabling -xcpm and KernelPM in Clover, but that doesn't seem to have any effect.  I still only have one P-State.  And the strange thing is, AppleIntelCPUPowerManagement is always loaded, even with these boot options.

  • 3 weeks later...
  • 4 years later...

Is this the same exact method for 10.11? I have a dell 7130 with a 4300y I'm trying to get 10.11 working on. I know its very old at this point but I have a cloned version from my acer w700 that I want to get to work as a challenge before upgrading to a newer osx version. 

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