32 bit kernel on 64 bit machine

From: erkrishna@gmail.com (er krishna)
To: kernelnewbies@lists.kernelnewbies.org
Subject: 32 bit kernel on 64 bit machine
Date: Fri, 20 Apr 2012 12:37:00 +0800	[thread overview]
Message-ID: <CAMGjyMsraad4Po7J8EMD-Ypdx6r4vZTzi9kq7pUdbCFY9CyNFA@mail.gmail.com> (raw)
In-Reply-To: <CALButCLR9+acCuHNYy-nFNYXhQKhd96v4C+R3JxkD2vOL=Xixw@mail.gmail.com>

On Apr 20, 2012 12:16 PM, "Graeme Russ" <graeme.russ@gmail.com> wrote:
>
> Hi Krishna,
>
> Please keep ML Cc'd
yep
>
> On Fri, Apr 20, 2012 at 1:57 PM, er krishna <erkrishna@gmail.com> wrote:
> > Graeme,
> >
> > Thanks for the reply.
> >
> > On Fri, Apr 20, 2012 at 11:49 AM, Graeme Russ <graeme.russ@gmail.com>
wrote:
> >>
> >> Hi Krishna,
> >>
> >> On Fri, Apr 20, 2012 at 1:45 PM, er krishna <erkrishna@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.
>
> >> > 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.

> 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?
>
> Regards,
>
> Graeme
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