64 or 32 bit kernel?

Running a Q9550, full 64 bit kernel and extensions in 10.6.8.

Only 32 bit in 10.7, just wondered if anyone with the same or similar CPU spec is running at 64, tried to boot with a modified argument in boot.plist and it sticks at boot.

Thanks a lot.

LosChristianos said:

Running a Q9550, full 64 bit kernel and extensions in 10.6.8.

Only 32 bit in 10.7, just wondered if anyone with the same or similar CPU spec is running at 64, tried to boot with a modified argument in boot.plist and it sticks at boot.

Thanks a lot.

Click to expand...

What is the difference anyways in booting your system at either 32 or 64 bits? I never booted my system into 64 bits, and I would like to know if there would be any benefits?

kmair said:

LosChristianos said:

Running a Q9550, full 64 bit kernel and extensions in 10.6.8.

Only 32 bit in 10.7, just wondered if anyone with the same or similar CPU spec is running at 64, tried to boot with a modified argument in boot.plist and it sticks at boot.

Thanks a lot.

Click to expand...

What is the difference anyways in booting your system at either 32 or 64 bits? I never booted my system into 64 bits, and I would like to know if there would be any benefits?

Click to expand...

32-bit can only support 4GB Ram (among lots of other more technical issues pertaining to how the cpu cores are used). So, at a minimum, any memory >4GB is not being used if you are running a 32-bit OS.

ghorwith said:

32-bit can only support 4GB Ram (among lots of other more technical issues pertaining to how the cpu cores are used). So, at a minimum, any memory >4GB is not being used if you are running a 32-bit OS.

Click to expand...

That doesn't apply to OS X : http://en.wikipedia.org/wiki/Physical_Address_Extension

Yep as above it'll still recognise more than 4GB of RAM, I'm running 6.

A little more research reveals it's not 'that' important if you're running a 32 bit kernel instead of a 64.

Still interested to know why 10.6 is 64 and 10.7 is 32, is a Q9550 CPU considered so old now? I suppose a MacPro 3,1 is 3 years old.

mmaenpaa said:

ghorwith said:

32-bit can only support 4GB Ram (among lots of other more technical issues pertaining to how the cpu cores are used). So, at a minimum, any memory >4GB is not being used if you are running a 32-bit OS.

Click to expand...

That doesn't apply to OS X : http://en.wikipedia.org/wiki/Physical_Address_Extension

Click to expand...

I stand corrected (or guilty of coming from the Windows world, so hadn't considered the PAE OS X and other OS' use). Am I correct that in '32-bit' mode, any single application can only use 4 GB?

ghorwith said:

mmaenpaa said:

ghorwith said:

32-bit can only support 4GB Ram (among lots of other more technical issues pertaining to how the cpu cores are used). So, at a minimum, any memory >4GB is not being used if you are running a 32-bit OS.

Click to expand...

That doesn't apply to OS X : http://en.wikipedia.org/wiki/Physical_Address_Extension

Click to expand...

I stand corrected (or guilty of coming from the Windows world, so hadn't considered the PAE OS X and other OS' use). Am I correct that in '32-bit' mode, any single application can only use 4 GB?

Click to expand...

That is how I think it works.

From what I understand, booting into a 32-bit kernel does affect how the OS used the cores and memory (only 4GB of RAM can be utilized usually) BUT Applications that are 64-bit running on the 32-bit kernel are just fine. Those 64-bit apps can utilize all the RAM that is available to them beyond the 4GB cap. This is the case when it comes to Mac OS X. I can't speak for Windows. If you want to know what apps are running in 64-bit then you can open the Activity Monitor. On the right side of the list you will see where it says 64-bit for each application that it supports. If it is blank then it only runs in 32-bit mode. I hope this helps.

macaddictcr said:

If you want to know what apps are running in 64-bit then you can open the Activity Monitor. On the right side of the list you will see where it says 64-bit for each application that it supports. If it is blank then it only runs in 32-bit mode. I hope this helps.

Click to expand...

Good point didn't think of that, thanks a lot!