[uClinux-dev] Re: Not getting a good CF-image with Snapgear-3.3...

[David McCullough]

Jivin Evert lays it down ...
> 
> David McCullough wrote:
> >Jivin Evert lays it down ...
> >>Hi all!
> >>David McCullough wrote:
> >>>Jivin Evert lays it down ...
> >>>>Hi all!
> >>>>
> >>>>I'm trying to build a usable Snapgear install, but am running into 
> >>>>problems at the end when the CF-image is being assembled. Looks like 
> >>>>the mbr generated is not complete/valid.
> >>>This would be more appropriately posted on the uClinux-dev list.
> >>Thanks for the tip. I will continue my quest there!  :-)
> >>
> >>>>Here's some output:
> >>>>
> >>>>>dd if=/dev/zero of=mbr.img bs=512 count=1
> >>>>>1+0 records in
> >>>>>1+0 records out
> >>>>>echo -e "1,121343,L,*\n,,61,-" | sfdisk -uS -C 490 -H 8 -S 32 mbr.img
> >>>>>Warning: mbr.img is not a block device
> >>>>>Disk mbr.img: cannot get geometry
> >>>>>
> >>>>>Disk mbr.img: 490 cylinders, 8 heads, 32 sectors/track
> >>>>>
> >>>>>sfdisk: seek error: wanted 0x0000000000000000, got 0x0000000000000000
> >>>>>mbr.img: unrecognized partition table type
> >>>>>Old situation:
> >>>>>No partitions found
> >>>>>New situation:
> >>>>>Units = sectors of 512 bytes, counting from 0
> >>>>>
> >>>>> Device Boot    Start       End   #sectors  Id  System
> >>>>>mbr.img1   *         1    121343     121343  83  Linux
> >>>>>mbr.img2        121344    125439       4096  61  SpeedStor
> >>>>>mbr.img3             0         -          0   0  Empty
> >>>>>mbr.img4             0         -          0   0  Empty
> >>>>>
> >>>>>sfdisk: seek error: wanted 0x0000000000000000, got 0x0000000000000000
> >>>This is the problem I guess,  everything else looks about right.  Why I
> >>>don't understand is that the error is complaining that it got what
> >>>it wanted :-)
> >>>
> >>>What version of sfdisk do you have installed ?  Can you try a different
> >>>version ?
> >>I use the following version:
> >>sfdisk version 3.08 (aeb at cwi.nl, 040824) from util-linux-2.12r
> >
> >Thats the same version I have on my system.
> >
> >Are you running a 64bit OS by any chance ?
> 
> Nope. Regular 32-bit system on a P4 processor.

ok.

> >>This is the one that comes with Gentoo Linux (stable). Are there any 
> >>known problems with this version? If so, which newer (or older?) version 
> >>should I go for instead?
> >
> >Try running the commands by hand,  try strace on them and see what is being
> >returned.
> 
> Which would be the exact command that generates the error?
> Is it:
> echo -e "1,`expr $(CYLS) \\* $(HEADS) \\* $(SECTORS) - $(CONFIG) - 
> 1`,L,*\n,,61,-" | sfdisk -uS -C $(CYLS) -H $(HEADS) -S $(SECTORS) mbr.img

Yes,  but it's not that easy unfortunately.

> >Could be a problem with the fdisk source and the way it implements
> >llseek.  You could use the source from uClinux-dist/user/fdisk to 
> >see if you find why it is going bad.
> 
> Hmm... I can give that a try, but I'm not sure whether my debugging skills 
> are sufficient enough for it...   :-/

Ok,  I'll give it a go and make sure nothing has gone astray.  It's been
a while since I built one of those,

Cheers,
Davidm

-- 
David McCullough,  david_mccullough at securecomputing.com,   Ph:+61 734352815
Secure Computing - SnapGear  http://www.uCdot.org http://www.cyberguard.com