# Question about /usr/src/linux/.config

## Duncan Mac Leod

Can I use (copy) my .config file (/usr/src/linux/.config) from my 64bit kernel to another box running a 32bit kernel without modification?

I don't want to go through every part in menuconfig again.

To be more specific - is anything stored in .config which is x64 / x86 specific ? Ok - I should select the specific CPU config, but are all other things the same?

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## depontius

 *Duncan Mac Leod wrote:*   

> Can I use (copy) my .config file (/usr/src/linux/.config) from my 64bit kernel to another box running a 32bit kernel without modification?
> 
> I don't want to go through every part in menuconfig again.
> 
> To be more specific - is anything stored in .config which is x64 / x86 specific ? Ok - I should select the specific CPU config, but are all other things the same?

 

Can't do, at least not as simply as you say:

 *Quote:*   

> $ grep 64 .config
> 
> CONFIG_64BIT=y
> 
> CONFIG_X86_64=y
> ...

 

As you can see, a fair number of these are specific to 64-bit architecture.  What you might be able to do is copy this to a 32-bit machine, then start tweaking to turn it back to 32-bit.  I got to my 64-bit .config files by starting with old 32-bit, then doing the 64-bit tweaks.  Looking at what I've just posted, I see a number of places to possibly tweak, myself.  I need to read the help text before simply turning things on or off, though.  After all, there is a lot of ancient history in this file, some of which may be sub-optimal.

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## krinn

kernel options use dependencies, that's why you must enable something sometimes to enable another thing.

and i'm 99% sure that just disable 64bits to enable 32bits will disable every options a 32bits kernel couldn't use, it will also enable 32bits options that your current 64bits config couldn't select (i only have one in mind, the memory selection).

So for me as easy as going in the menu and just uncheck 64bits kernel option should be enough.

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