RE: x86_64_defconfig and i386_defconfig: What is the difference?

To add to this, if you're trying to compile a kernel to work for a specific
platform or board and it's not working, 'make menuconfig' is your friend for
taking a bare bones kernel .config and making it your own.



-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Tuesday, September 09, 2014 10:28 AM
To: Matthias Brugger
Cc: Rajat Jain; [email protected]; kernelnewbies
Subject: Re: x86_64_defconfig and i386_defconfig: What is the difference?

On Tue, 09 Sep 2014 16:06:07 +0200, Matthias Brugger said:

> > Can someone tell me if the i386 one is to be used when we want to 
> > build for a 32bit machine and the x86_64 is to be used for 64 bit
machine?
>
> You can build the kernel with any architecture for any architecture.
> This is called cross-compiling. The homepage [0] should explain you 
> how to do that.

Right, but you still need to use a .config appropriate for the target
machine, which is what I think Rajat was asking about.

A defconfig is usually only known verified to boot on a few (possibly one)
examples of that architecture hardware.  For embedded ARM, it may be one
specific development board or hardware device.  For x86, I think they try to
keep it "will probably kind of sort of boot on generic PC hardware with a
common distro, but anything fancylike a webcam or better graphics than "vga
tty emulation" may not work".

A defconfig is pretty much just a proof of concept starting point for an
actual working config for a given hardware system.