Arch Linux

PaulBx1

Member

Registered: 2008-10-18

Posts: 142

"Missing operating system" at boot after new install [SOLVED]

Hello all. Guess this is my first post.

I did try searching, looking at the install manual, etc. Didn't find much for this one.

Prior to install I had a blank space up front on the hard drive (cleared NTFS partition), a FAT32 partition sda2 with general files including my Puppy Linux pupsave file, and an OpenBSD partition with multiple slices on sda3. The mbr was set up with a simple multi-boot facility from OpenBSD. This is a Sony VGN-C140G laptop.

I installed Arch with the CD (ftp install), taking half of the free space up front in a single ext3 partition (sda1) for Arch, and made it bootable. No swap partition. When I booted I got the "Missing operating system" message. That is all I ever get.

I booted Puppy off CD like I usually do. I went into gparted and the sda1 partition needed a "check" (e2fsck I imagine), but otherwise looked fine there. I tried installing grub from puppy to replace any possible problem with the OpenBSD mbr, putting the /boot/grub stuff on sda1. In fact there is no problem looking at sda1 from puppy, all files seem to be there from the install. Anyway installing grub did not help.

I looked at the mbr with a hex editor, first copying it locally with dd. It did have the "aa55" word at the end, the lack of which would cause the "Missing operating system" message if I'm not mistaken. The lba part of the partition records looked right, although the cyl/head/sector portion looked wrong on sda2 and sda3. I'm guessing this part is not used any more. Running cfdisk from the Arch install showed things looking good, but cfdisk from puppy showed the strange cyl/head/sector stuff:

Partition Table for /dev/sda

         ---Starting---      ----Ending----    Start     Number of
 # Flags Head Sect Cyl   ID  Head Sect Cyl     Sector    Sectors
-- ----- ---- ---- ---- ---- ---- ---- ---- ----------- -----------
 1  0x80    1    1    0 0x83  254   63 1023          63    58588992
 2  0x00  254   63 1023 0x0B  254   63 1023   117210240    58621185
 3  0x00  254   63 1023 0xA6  254   63 1023   175831425    58605120
 4  0x00    0    0    0 0x00    0    0    0           0           0

However looking at it with the "sector" printout looked OK, just like the arch cfdisk did:

Partition Table for /dev/sda

               First       Last
 # Type       Sector      Sector   Offset    Length   Filesystem Type (ID) Flag
-- ------- ----------- ----------- ------ ----------- -------------------- ----
 1 Primary           0    58589054     63    58589055 Linux (83)           Boot
   Pri/Log    58589055   117210239      0    58621185 Free Space           None
 2 Primary   117210240   175831424      0    58621185 W95 FAT32 (0B)       None
 3 Primary   175831425   234436544      0    58605120 OpenBSD (A6)         None

I looked also at the beginning of sda1, sda2 and sda3 for "partition boot records", I suppose they are called. sda2 and sda3 both had them (sda2's had a single error message in it saying "not a bootable partition", as expected). Both of these also had the "aa55" signature at the end. There was just all zeros in the sda1 "pbr", with no "aa55". I am guessing it should have one, and the lack is why I get "Missing operating system". Is this correct?

Last edited by PaulBx1 (2009-03-21 05:27:37)

roels

Member

Registered: 2009-03-19

Posts: 8

Re: "Missing operating system" at boot after new install [SOLVED]

I had the same problem when I interupted the instalation after setting up the drives and mountpoints. When I reinstalled arch, there were no problems anymore.
Maby you should check your /etc/fstab for your mount points. Are sda1 ..etc in there?

PaulBx1

Member

Registered: 2008-10-18

Posts: 142

Re: "Missing operating system" at boot after new install [SOLVED]

I did not interrupt the install. /etc/fstab has this:

# 
# /etc/fstab: static file system information
#
# <file system>        <dir>         <type>    <options>          <dump> <pass>
none                   /dev/pts      devpts    defaults            0      0
none                   /dev/shm      tmpfs     defaults            0      0

#/dev/cdrom             /media/cd   auto    ro,user,noauto,unhide   0      0
#/dev/dvd               /media/dvd  auto    ro,user,noauto,unhide   0      0
#/dev/fd0               /media/fl   auto    user,noauto             0      0

UUID=c14d08a8-d765-4940-84bf-22e3c22b231e / ext3 defaults 0 1

However, the error message is issued by the code in the mbr, which is long before any problem in fstab would show up. I still need to know if the / partition in arch has a "partition boot record". Just doing a dd command should tell you this, e.g.:

dd if=/dev/sda1 count=1 bs=512|hexdump -C

... if your / partition is on sda1. Look for a "55 aa" at the end.

PaulBx1

Member

Registered: 2008-10-18

Posts: 142

Re: "Missing operating system" at boot after new install [SOLVED]

Well, I fixed this problem by ripping out the whole install and doing it over again. This time I installed grub via arch, not puppy. That got me a significantly different mbr. The "pbr" for sda1 was still all zeros, but it did not matter because it booted anyway. I don't know if the arch grub was the thing that fixed it, as I changed a few other things (like having a separate /boot partition) but I'm guessing that was it.