Problem with kernel image in a Prep Boot on PowerPC

Problem with kernel image in a Prep Boot on PowerPC

[Márcio Oliveira]

Hi There!

   I have a IBM Power server and I want to put the /boot partition onto 
softwrae RAID1 array, but I'm having some problems...

   Aparently yaboot boot loader doesn't support /boot partition on a 
linux software RAID 1, so i'm trying to put the kernel image 
(zImage.initrd) directly on the Prep Boot partition. But when the system 
boots, the kernel can't locate the initrd or the root partition ("Kernel 
Panic" no init found message).

   I think the kernel is pointing to the wrong root partiotion. In a x86 
box, I can change the kernel root partition in the boot loader (root= 
parameter) or using the "rdev" command. In my case, the IBM Power 
doesn't have a boot loader (yaboot was replaced by the kernel image) and 
the powerpc64 system doesn't have the rdev command (from util-linux 
package, the same package on x86 systems have the rdev command!).

   Is there a way to change the default root partition in my ppc64 
kernel image?

   I followed this steps to made the configuration of the kernel image:

# cd /usr/src/linux-2.4
# cp /boot/config-2.4.21-4.EL swinitrd.config
Edit the file Makefile to change the EXTRAVERSION variable to match the 
running kernel: EXTRAVERSION= -4.EL
# cp /boot/initrd-2.4.21-4.EL.img 
/usr/src/linux-2.4/arch/ppc64/boot/ramdisk.image.gz
# cd /usr/src/linux-2.4
# make distclean
# cp swinitrd.config .config
# make oldconfig
# make dep
# make zImage.initrd
# cp /usr/src/linux-2.4/arch/ppc64/boot/zImage.initrd 
/boot/zImage.initrd-2.4.21-4.EL
# cp /usr/src/linux-2.4/swinitrd.config /boot/config.initrd-2.4.21-4.EL
# dd if=/boot/zImage.initrd-2.4.21-4.EL of=/dev/sdb1 bs=512

   This is my partition scheme:

Disk 1:
/dev/sda1   = Prep Boot Partition (10MB)
/dev/sda2   = RAID 1 - "/boot" partition (100MB)
/dev/sda3   = swap (300MB)
/dev/sda4   = Extendend
/dev/sda5   = RAID 1 - "/" root partition (34GB)

Disk 2:
/dev/sdb1   = Prep Boot Partition (10MB)
/dev/sdb2   = RAID 1 - "/boot" partition (100MB)
/dev/sdb3   = swap (300MB)
/dev/sdb4   = Extendend
/dev/sdb5   = RAID 1 - "/" root partition (34GB)

   Any ideia about this issue?

Thanks a lot!

Márcio.

Re: Problem with kernel image in a Prep Boot on PowerPC

[John W. Linville]

On Wed, Aug 24, 2005 at 12:05:25PM -0300, Márcio Oliveira wrote:

>   I think the kernel is pointing to the wrong root partiotion. In a x86 
> box, I can change the kernel root partition in the boot loader (root= 
> parameter) or using the "rdev" command. In my case, the IBM Power 
> doesn't have a boot loader (yaboot was replaced by the kernel image) and 
> the powerpc64 system doesn't have the rdev command (from util-linux 
> package, the same package on x86 systems have the rdev command!).

I don't know anything that will do this on a pre-built kernel.  But,
you should look at CONFIG_CMDLINE_BOOL and CONFIG_CMDLINE in your
kernel configuration.  That will let you pre-configure the "root="
command line option.

I don't know if ppc64 can use the zImage-style boot wrapper.  If it
can, that would provide you with an option of modifying the command
line at boot time if needed.

Good luck!

John
-- 
John W. Linville
linville@tuxdriver.com

Re: Problem with kernel image in a Prep Boot on PowerPC

[Márcio Oliveira]

John W. Linville wrote:

>On Wed, Aug 24, 2005 at 12:05:25PM -0300, Márcio Oliveira wrote:
>
>  
>
>>  I think the kernel is pointing to the wrong root partiotion. In a x86 
>>box, I can change the kernel root partition in the boot loader (root= 
>>parameter) or using the "rdev" command. In my case, the IBM Power 
>>doesn't have a boot loader (yaboot was replaced by the kernel image) and 
>>the powerpc64 system doesn't have the rdev command (from util-linux 
>>package, the same package on x86 systems have the rdev command!).
>>    
>>
>
>I don't know anything that will do this on a pre-built kernel.  But,
>you should look at CONFIG_CMDLINE_BOOL and CONFIG_CMDLINE in your
>kernel configuration.  That will let you pre-configure the "root="
>command line option.
>  
>
Hi John,

The command rdev can change the default root partition on x86 linux 
systems with pre-built kernels.

About the CONFIG_CMDLINE in the kernel configuration, I found it in lots 
of files in the kernel source tree and I'd like to know which file I 
need to change this value (/usr/src/linux/arch/ppc64/defconfig ?).

>I don't know if ppc64 can use the zImage-style boot wrapper.  If it
>can, that would provide you with an option of modifying the command
>line at boot time if needed.
>  
>
According to this doc: 
http://www-128.ibm.com/developerworks/eserver/library/es-SW_RAID_LINUX.html, 
ppc64 can use zImage-style boot wrapper, so I'm trying it.

>Good luck!
>
>John
>  
>
Thanks John!

Márcio.

Re: Problem with kernel image in a Prep Boot on PowerPC

[John W. Linville]

On Wed, Aug 24, 2005 at 02:52:44PM -0300, Márcio Oliveira wrote:

> The command rdev can change the default root partition on x86 linux 
> systems with pre-built kernels.
 
Of course...I meant I don't know of anything like that for PPC.

> About the CONFIG_CMDLINE in the kernel configuration, I found it in lots 
> of files in the kernel source tree and I'd like to know which file I 
> need to change this value (/usr/src/linux/arch/ppc64/defconfig ?).
 
Probably just in your .config file:

	cp arch/ppc64/defconfig .config
	vi .config # Change CONFIG_CMDLINE here
	make oldconfig

> According to this doc: 
> http://www-128.ibm.com/developerworks/eserver/library/es-SW_RAID_LINUX.html, 
> ppc64 can use zImage-style boot wrapper, so I'm trying it.

Cool...I think you will like having that as an option.

John
-- 
John W. Linville
linville@tuxdriver.com