32 bit kernel on 64 bit machine

[Graeme Russ]

Hi Krishna,

On Fri, Apr 20, 2012 at 2:37 PM, er krishna <erkrishna at gmail.com> wrote:
>
> On Apr 20, 2012 12:16 PM, "Graeme Russ" <graeme.russ at gmail.com> wrote:
>>
>> Hi Krishna,
>>
>> Please keep ML Cc'd
> yep
>
>>
>> On Fri, Apr 20, 2012 at 1:57 PM, er krishna <erkrishna at gmail.com> wrote:
>> > Graeme,
>> >
>> > Thanks for the reply.
>> >
>> > On Fri, Apr 20, 2012 at 11:49 AM, Graeme Russ <graeme.russ at gmail.com>
>> > wrote:
>> >>
>> >> Hi Krishna,
>> >>
>> >> On Fri, Apr 20, 2012 at 1:45 PM, er krishna <erkrishna at gmail.com>
>> >> wrote:
>> >> > Hi All,
>> >> >
>> >> > Is it possible to boot the 64 bit machine through 32 bit compiled
>> >> > kernel
>> >> > ? I
>> >>
>> >> Yes
>> >
>> >
>> > How ? What are the exact steps ? I mean how I will compile the kernel
>> > (flags
>> > and all) that will boot on 64 bit processor ? My problem is I have 64
>> > bit
>> > fc16 and Sandybridge 64 bit machine. I need to compile the kernel for 32
>> > bit
>> > with these setup and boot it.
>>
>> The steps you performed I believe will have built a 32-bit kernel
> yes but when booted it panic during initramfs stage.

Is the initramfs the Fedora init ramfs? If so, maybe it has 64-bit user space

>> >> > tried its compilation on fedora 16 64 bit and intel sandybridge 64
>> >> > bit
>> >> > with
>> >> > following option:
>> >> >
>> >> >
>> >> > $ make ARCH=i386 menuconfig
>> >> >
>> >> > $ make ARCH=i386 –j4
>> >> >
>> >> >
>> >> > but it failed to boot. Any suggestion if it can be done by any way.
>> >>
>> >> You cannot use a 32-bit kernel with 64-bit user-space
>> >>
>> >
>> > Sorry, I didn't get you here. Do you mean to say that 64 bit application
>> > won't work on 32 bit kernel. if its then its fine.
>>
>> Yes, that is what I mean't - If all you userspace (libraries,
>> applications etc) are 64-bit then a 32-bit kernel cannot run them. You
>> should have at least got a kernel panic that init could not be run
>>
> application will not run that i m agreed but the booting should be smooth.
> Isnt it?
>
> I got panic during early stage of booting before calling of init.

Can you post a log? You'll need to setup logging to serial or net console

>> By 'fine' you mean that your setup is fine and you tried to run the
>
> No it was not intended to say like this.  But first of all booting didnt
> happen.
> So there is no point of trying any application.
>
> Can you pls tell that booting and 32 bit application should run smoothly?
>
>> 32-bit kernel using 32-bit userspace? If so, there is obviously
>> another problem.
>
> Watt problem?

I would say the initramfs contains 64-bit user-space

Regards,

Graeme