Re: grub2 on power6 box.

[Manoel Rebelo Abraches]

On Fri, 2010-07-23 at 11:39 -0400, Lennart Sorensen wrote:
> On Fri, Jul 23, 2010 at 09:57:37AM -0400, Lennart Sorensen wrote:
> > On Fri, Jul 23, 2010 at 07:56:27AM +0200, Vladimir 'φ-coder/phcoder' 
> > Serbinenko wrote:
> > > On 07/22/2010 11:23 PM, Lennart Sorensen wrote:
> > > > I am trying to use grub2 to boot an IBM p520 power6 box.  I know yaboot
> > > > can do the job, but it doesn't deal with software raid, ext4, LVM or
> > > > anything else useful.
> > > >
> > > > I have managed to get as far as booting to a grub prompt from disk.
> > > > Unfortunately it doesn't appear to be seeing any disks at that point.
> > > >
> > > > The way I got it this far was to create an 8MB (smallest cfdisk would
> > > > make) PReP boot partition, and then run grub-mkimage -n -o /tmp/grub -O
> > > > powerpc-ieee1275 *.mod in the ieee1275 grub directory.  I then dd'd
> > > > /tmp/grub to /dev/sda1 (the PReP boot partition).
> > > >
> > > >   
> > > You need to add -p "<your /boot/grub in grub notation>". Also avoid the
> > > raid and lvm-related modules you don't need. OFW exposes ghost devices
> > > so assembling raids which involves looking at all devices is slow
> > 
> > I will try that (although I think I did).
> > 
> > I can't even get it to do ls on any disk or anything.  It really seems
> > to be behaving as if it doesn't detect any disks.
> 
> So I fixed ofpathname (it was not working because it did find /sys -name
> $device, which mathes multiple things on modern kernels).  I changed the
> find to find /sys -type d -name $device and now that works.  So now I
> can run grub-install, but of course that just creates a /boot/grub/grub
> file with the main grub and a filesystem module attached.  It doesn't
> actually boot.
> 
> It set the
> boot_device=/address@hidden/pci1014,address@hidden/sas/address@hidden:4,\grub
> 
> /dev/sda4 is a fat16 partition mounted as /boot/grub.  Unfortunately I
> am not convinced the IBM boxes know how to read filesystems or boot
> files.  It seems it only wants to read raw from a PReP boot partition.
OF can read FAT12 filesystem.
you could format it with fat 12 and then mount it at /boot/grub.
then you can use grub-install and grub-mkconfig to create a grub.cfg
 I think the easiest way  is to set a devalias in OF to point to you
device:
devalias hd /address@hidden/pci1014,address@hidden/sas/address@hidden 
then it should appear when you use the 'ls' command.
you could also set boot-device to
hd:<parnumber>,grub 
since OF can read FAT12 filesystem it will be able to find grub there.


> So when I dd /boot/grub/grub to /dev/sda1 (an 8MB PReP boot partition)
> the system does start grub, but of course since grub was only the core
> plus the fat module, it just says:
> 
> Welcome to GRUB!                                                              
>                                                                               
>                                                                               
>                                      
>                                                                               
>                                                                               
>                                                                               
>                                      
> error: no device is set.
> Entering rescue mode...                                                       
>                                                                               
>                                                                               
>                                      
> grub rescue>
> 
> So what do I do then to get it to know what device to use?
> 

-- 
Best Regards,

Manoel Rebelo Abranches
Software engineer
IBM - Linux Technology Center - Brazil