Little endian.

Little endian.

[Nicu Popovici]

Hello ,

I have the follwing problem. I setup a HardHat distribution on a mips
machine ( an ATLAS board) and everithing runs fine in big-endian mode.
Now I want to run the board inlittle endian mode so I took the
linux/mipsel distribution , I did the same steps as with big-endian
distribution. I run load tftp:/linux/mipsel/vmlinux-el.srec and it works
fine . Then I issue the command go . root=/dev/sda1 ( I do not install
the HardHat again ???? maybe here it is the problem ) I get the
following error.
==========================================================
VFS: Mounted root (ext2 filesystem) readonly.
Freeing prom memory: 1020k freed
Freeing unused kernel memory: 68k freed
Kernel panic: No init found.  Try passing init= option to kernel.
==========================================================
So please tell me where did I go wrong ?

Nicu

Re: Little endian.

[Kevin D. Kissell]

If you want to run little-endian, you need to install
the little-endian binaries and libraries.  Since I needed
to "swing both ways", I put both a big-endian root and
a little-endian root partition on my Atlas disk, with user/data 
partitions that can be mounted on either one - fortunately, 
the Ext2FS metadata seems to be consistent regardless 
of endianness.

            Kevin K.

----- Original Message ----- 
From: "Nicu Popovici" <octavp@isratech.ro>
To: <linux-mips@oss.sgi.com>
Sent: Saturday, December 16, 2000 2:04 AM
Subject: Little endian.


> Hello ,
> 
> I have the follwing problem. I setup a HardHat distribution on a mips
> machine ( an ATLAS board) and everithing runs fine in big-endian mode.
> Now I want to run the board inlittle endian mode so I took the
> linux/mipsel distribution , I did the same steps as with big-endian
> distribution. I run load tftp:/linux/mipsel/vmlinux-el.srec and it works
> fine . Then I issue the command go . root=/dev/sda1 ( I do not install
> the HardHat again ???? maybe here it is the problem ) I get the
> following error.
> ==========================================================
> VFS: Mounted root (ext2 filesystem) readonly.
> Freeing prom memory: 1020k freed
> Freeing unused kernel memory: 68k freed
> Kernel panic: No init found.  Try passing init= option to kernel.
> ==========================================================
> So please tell me where did I go wrong ?
> 
> Nicu
> 

Re: Little endian.

[Kevin D. Kissell]

If you want to run little-endian, you need to install
the little-endian binaries and libraries.  Since I needed
to "swing both ways", I put both a big-endian root and
a little-endian root partition on my Atlas disk, with user/data 
partitions that can be mounted on either one - fortunately, 
the Ext2FS metadata seems to be consistent regardless 
of endianness.

            Kevin K.

----- Original Message ----- 
From: "Nicu Popovici" <octavp@isratech.ro>
To: <linux-mips@oss.sgi.com>
Sent: Saturday, December 16, 2000 2:04 AM
Subject: Little endian.


> Hello ,
> 
> I have the follwing problem. I setup a HardHat distribution on a mips
> machine ( an ATLAS board) and everithing runs fine in big-endian mode.
> Now I want to run the board inlittle endian mode so I took the
> linux/mipsel distribution , I did the same steps as with big-endian
> distribution. I run load tftp:/linux/mipsel/vmlinux-el.srec and it works
> fine . Then I issue the command go . root=/dev/sda1 ( I do not install
> the HardHat again ???? maybe here it is the problem ) I get the
> following error.
> ==========================================================
> VFS: Mounted root (ext2 filesystem) readonly.
> Freeing prom memory: 1020k freed
> Freeing unused kernel memory: 68k freed
> Kernel panic: No init found.  Try passing init= option to kernel.
> ==========================================================
> So please tell me where did I go wrong ?
> 
> Nicu
> 

Re: Little endian.

[Ralf Baechle]

On Fri, Dec 15, 2000 at 07:28:15PM +0100, Kevin D. Kissell wrote:

> If you want to run little-endian, you need to install
> the little-endian binaries and libraries.  Since I needed
> to "swing both ways", I put both a big-endian root and
> a little-endian root partition on my Atlas disk, with user/data 
> partitions that can be mounted on either one - fortunately, 
> the Ext2FS metadata seems to be consistent regardless 
> of endianness.

Ext2fs on-disk data structures are defined to be little endian.  Some very
old ext2 filesystems which afaik where all created on Linux/M68K were big
endian; for those e2fsck has the option to change the endianess of the
filesystem during a fsck run; the current kernel will refuse to accept
such big endian ext2 filesystems.

  Ralf

Re: Little endian.

[Geert Uytterhoeven]

On Sat, 16 Dec 2000, Ralf Baechle wrote:
> On Fri, Dec 15, 2000 at 07:28:15PM +0100, Kevin D. Kissell wrote:
> > If you want to run little-endian, you need to install
> > the little-endian binaries and libraries.  Since I needed
> > to "swing both ways", I put both a big-endian root and
> > a little-endian root partition on my Atlas disk, with user/data 
> > partitions that can be mounted on either one - fortunately, 
> > the Ext2FS metadata seems to be consistent regardless 
> > of endianness.
> 
> Ext2fs on-disk data structures are defined to be little endian.  Some very
> old ext2 filesystems which afaik where all created on Linux/M68K were big
> endian; for those e2fsck has the option to change the endianess of the
> filesystem during a fsck run; the current kernel will refuse to accept
> such big endian ext2 filesystems.

For correctness: early Linux/PPC used big-endian ext2 as well. IIRC we switched
to little-endian ext2 on m68k in late 1996, and on PPC in late 1997 / early
1998.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

Re: Little endian.

[Carsten Langgaard]

I guess, what you want to do is to install a little endian system from a
nfs-server, as you probably did with the bigendian system. If this is the
case then you shouldn't issue the 'go . root=/dev/sda1' command, as you
haven't installed the root filesystem yet.
Instead you should use this command: 'go . nfsroot=<ipaddr-of-nfsserver>
....'

/Carsten

Nicu Popovici wrote:

> Hello ,
>
> I have the follwing problem. I setup a HardHat distribution on a mips
> machine ( an ATLAS board) and everithing runs fine in big-endian mode.
> Now I want to run the board inlittle endian mode so I took the
> linux/mipsel distribution , I did the same steps as with big-endian
> distribution. I run load tftp:/linux/mipsel/vmlinux-el.srec and it works
> fine . Then I issue the command go . root=/dev/sda1 ( I do not install
> the HardHat again ???? maybe here it is the problem ) I get the
> following error.
> ==========================================================
> VFS: Mounted root (ext2 filesystem) readonly.
> Freeing prom memory: 1020k freed
> Freeing unused kernel memory: 68k freed
> Kernel panic: No init found.  Try passing init= option to kernel.
> ==========================================================
> So please tell me where did I go wrong ?
>
> Nicu

Little Endian

[ellis]

I'm just starting to look at a porting project. The board I'll
be using is little endian and the CVS version of the kernel
source doesn't have anything but big endian in the config
menu. Does little endian work at all and if so, how do I 
select it?

--
http://www.spinics.net/linux/

Re: Little Endian

[Manish Lachwani]

ellis@spinics.net wrote:

>I'm just starting to look at a porting project. The board I'll
>be using is little endian and the CVS version of the kernel
>source doesn't have anything but big endian in the config
>menu. Does little endian work at all and if so, how do I 
>select it?
>
>--
>http://www.spinics.net/linux/
>
>  
>
When you do "make menuconfig", under "Machine Selection" item, there is 
an option called "Generate little endian code". Is this what you are 
looking for? This is a config option CONFIG_CPU_LITTLE_ENDIAN. This is 
defined in arch/mips/Kconfig:

config CPU_LITTLE_ENDIAN
        bool "Generate little endian code"
        default y if ACER_PICA_61 || CASIO_E55 || DDB5074 || DDB5476 || 
DDB5477 || MACH_DECSTATION
|| IBM_WORKPAD || LASAT || MIPS_COBALT || MIPS_ITE8172 || MIPS_IVR || 
SOC_AU1X00 || NEC_OSPREY || OLIVETTI_M700 || SNI_RM200_PCI || 
VICTOR_MPC30X || ZAO_CAPCELLA
        default n if MIPS_EV64120 || MIPS_EV96100 || MOMENCO_OCELOT || 
MOMENCO_OCELOT_G || SGI_IP22 || SGI_IP27 || SGI_IP32 || TOSHIBA_JMR3927
        help
          Some MIPS machines can be configured for either little or big 
endian
          byte order. These modes require different kernels. Say Y if your
          machine is little endian, N if it's a big endian machine.
                                                                                                   

Thanks
Manish Lachwani