"Unhandled real mode interrupt!" Error on boot

jdmoore0883 · Apr 13, 2015, 3:31 PM

I downloaded the 1GB image and used dd to get it to the CF Card. No issues at all here.

The device boots, gets to the bootloader, and as soon as I choose a boot option, I get an error: "Unhandled real mode interrupt!"

Here is the console output:

Loading master boot sector...
Transferring control to the master bootstrap loader...

1  pfSense
2  pfSense
5  Drive 1

F6 PXE
Boot:  1 ###
Unhandled real mode interrupt!
Vector: 0x00000013
CS:IP = 0000:076E
SS:ESP = 0000:7BEC
EAX = 4200  EBX = 7C00  ECX = 0001  EDX = 0180
ESI = 7BEC  EDI = 7BFC  EBP = 0800  FLG = 7006
DS  = 0000      ES =  0000      FS  = 0000      GS  = 0000
Stack:
   7BEC: 0010 7C00 003F 0000
   7BFC: 07BE 31FC 8EC0 BCD0
   7C0C: E689 B906 A5F3 08B1
   7C1C: 45FE 8A00 20B7 4E80

I don't know where to even really start with this… Any ideas?

charliem · Apr 14, 2015, 12:45 AM

@jdmoore0883:

I don't know where to even really start with this… Any ideas?

You could start with a description of the hardware you are trying to use.

jdmoore0883 · Apr 14, 2015, 1:30 PM

Hardware is a Nokia IP260.

Intel Celeron CPU
512MB RAM
1GB Flash Card
40GB HDD (currently disconnected)

Anything else?

charliem · Apr 14, 2015, 2:56 PM

@jdmoore0883:

Hardware is a Nokia IP260.

https://forum.pfsense.org/index.php?topic=18978.0

jdmoore0883 · Apr 14, 2015, 3:01 PM

I had come across that very post as well.

Sadly, other than details on the problem, there is very little information on what to do about the error.

While there are indeed forum posts about IP560s, they all seem to indicate that there is no issue, just flash the card, put it on, boot, and done. Well, I am doing that same process and getting the above mentioned error.

I am not opposed to doing some kind of debugging or other stuff, but I don't even know where to start really.

My Google-Fu has not come up with any ideas about the error either.

charliem · Apr 14, 2015, 4:06 PM

The boot loader is trying to use INT13h, AH42, aka 'extended services read' to load the MBR, and appears to be failing. I'd guess the target device doesn't support that, and the bootloader may need to use CHS to access the device instead, like a floppy. Nokia presumably wrote the bios, so they could do what they wanted / needed to, without regards to booting a general purpose OS. But that's just a WAG.

Maybe try to boot a linux image, or a vanilla FreeBSD image, or booting from the HD. If you have a working IP260 CF, see what that looks like (partitioned like a disk, or a floppy image)

Doesn't appear many people have tried to re-purpose an IP260, and the few that have, have not been successful.

jdmoore0883 · Apr 15, 2015, 7:54 PM

Thanks for the info.

Using gparted, I can see the "partitioning" for pfSense on that card. When I try to reload gparted with the IPSO card in the reader, I get an error:
"Invalid partition table - recursive partition on /dev/sdb."

Doing some research on your INT13h and CHS comments, I decided to run command "sfdisk -l"

IPSO card:

Disk /dev/sdb: 1011 cylinders, 4 heads, 62 sectors/track
Warning: The partition table looks like it was made
  for C/H/S=*/256/63 (instead of 1011/4/62).
For this listing I'll assume that geometry.
Units = cylinders of 8257536 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1          0       -       0          0    0  Empty
/dev/sdb2          0       -       0          0    0  Empty
/dev/sdb3          0       -       0          0    0  Empty
/dev/sdb4   *      0       3-      4-     25000   a6  OpenBSD
		end: (c,h,s) expected (3,25,41) found (1023,255,63)

Disk /dev/sdb4: 201 cylinders, 4 heads, 62 sectors/track
Warning: The partition table looks like it was made
  for C/H/S=*/256/63 (instead of 201/4/62).
For this listing I'll assume that geometry.
Units = cylinders of 8257536 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb4p1          0       -       0          0    0  Empty
/dev/sdb4p2          0       -       0          0    0  Empty
/dev/sdb4p3          0       -       0          0    0  Empty
/dev/sdb4p4   *      0       3-      4-     25000   a6  OpenBSD
		end: (c,h,s) expected (3,25,41) found (1023,255,63)

pfSense card:

Disk /dev/sdb: 1009 cylinders, 32 heads, 62 sectors/track
Warning: The partition table looks like it was made
  for C/H/S=*/16/63 (instead of 1009/32/62).
For this listing I'll assume that geometry.
Units = cylinders of 516096 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1   *      0+    914     915-    461128+  a5  FreeBSD
/dev/sdb2        915+   1829     915-    461128+  a5  FreeBSD
		end: (c,h,s) expected (1023,15,63) found (805,15,63)
/dev/sdb3       1830    1931     102      51408   a5  FreeBSD
		start: (c,h,s) expected (1023,15,63) found (806,0,1)
		end: (c,h,s) expected (1023,15,63) found (907,15,63)
/dev/sdb4          0       -       0          0    0  Empty

I think that the CHS route is indeed the right track.

So I have narrowed it down to something to do with the MBR. Using the following command, I was able to extract the MBR for both cards:
dd if=/dev/sdb of=mbr bs=512 count=1

I then "converted" them to text with the following command:
xxd mbr > mbr.txt

IPSO MBR:

0000000: eb1b 9090 161f 666a 0051 5006 5331 c088  ......fj.QP.S1..
0000010: f050 6a10 89e5 e8be 008d 6610 cbfc 31c9  .Pj.......f...1.
0000020: 8ec1 8ed9 8ed1 bc00 7c89 e6bf 0007 fec5  ........|.......
0000030: f3a5 beee 7d80 fa80 722c b601 e867 00b9  ....}...r,...g..
0000040: 0100 bebe 8db6 0180 7c04 a675 07e3 19f6  ........|..u....
0000050: 0480 7514 83c6 10fe c680 fe05 72e9 49e3  ..u.........r.I.
0000060: e1be 7c7d eb52 31d2 8916 0009 b610 e835  ..|}.R1........5
0000070: 00bb 0090 8b77 0a01 debf 00b0 b900 ac29  .....w.........)
0000080: f1f3 a429 f930 c0f3 aae8 0300 e981 13fa  ...).0..........
0000090: e464 a802 75fa b0d1 e664 e464 a802 75fa  .d..u....d.d..u.
00000a0: b0df e660 fbc3 bb00 8c8b 4408 8b4c 0a0e  ...`......D..L..
00000b0: e853 ff73 21be 797d e813 00be 817d e80d  .S.s!.y}.....}..
00000c0: 0030 e4cd 16cd 19bb 0700 b40e cd10 ac84  .0..............
00000d0: c075 f4b4 01f9 c32e f606 8a08 8074 21bb  .u...........t!.
00000e0: aa55 52b4 41cd 135a 7216 81fb 55aa 7510  .UR.A..Zr...U.u.
00000f0: f6c1 0174 0b89 eeb4 42cd 13b0 ffe6 80c3  ...t....B.......
0000100: 52b4 08cd 1388 f55a 72cc 80e1 3f74 c4fa  R......Zr...?t..
0000110: 668b 4608 5266 0fb6 d966 31d2 66f7 f388  f.F.Rf...f1.f...
0000120: eb88 d543 30d2 66f7 f388 d75a 663d ff03  ...C0.f....Zf=..
0000130: 0000 fb77 9e86 c4c0 c802 08e8 4091 88fe  ...w........@...
0000140: 28e0 8a66 0238 e072 0288 e0bf 0500 c45e  (..f.8.r.......^
0000150: 0450 b402 cd13 5b73 0a4f 741c 30e4 cd13  .P....[s.Ot.0...
0000160: 93eb eb0f b6c3 0146 0873 03ff 460a d0e3  .......F.s..F...
0000170: 005e 0528 4602 7788 c352 6500 426f 6f74  .^.(F.w..Re.Boot
0000180: 0020 6572 726f 720d 0a00 0090 9090 9090  . error.........
0000190: 9090 9090 9090 9090 9090 9090 9090 9090  ................
00001a0: 9090 9090 9090 9090 9090 9090 9090 9090  ................
00001b0: 9090 9090 9090 9090 9090 9090 9090 0000  ................
00001c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00001d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00001e0: 0000 0000 0000 0000 0000 0000 0000 8000  ................
00001f0: 0100 a6ff ffff 0000 0000 50c3 0000 55aa  ..........P...U.
[/code]

pfSense MBR:
[code]0000000: fc31 c08e c08e d88e d0bc 007c 89e6 bf00  .1.........|....
0000010: 06b9 0001 f3a5 89fd b108 f3ab fe45 f2e9  .............E..
0000020: 008a f646 b720 7407 804e b740 8a56 b688  ...F. t..N.@.V..
0000030: 5600 52e8 f200 bbc2 0731 d288 6ffc 0fa3  V.R......1..o...
0000040: 56b7 7318 8a07 84c0 7412 bf84 07b1 08f2  V.s.....t.......
0000050: ae81 c706 008a 0d01 cfe8 bd00 4280 c310  ............B...
0000060: 73d9 582c 7f3a 0675 0472 0548 740d 30c0  s.X,.:.u.r.Ht.0.
0000070: 04b0 8846 b4bf ae07 e89e 00be 7207 e8b3  ...F........r...
0000080: 008a 56b5 4ee8 a500 eb05 b023 e8ac 0030  ..V.N......#...0
0000090: e4cd 1a89 d703 7ebc b403 e8a0 00f6 c401  ......~.........
00000a0: 7511 30e4 cd1a 39fa 72ee 8a46 b580 4eb7  u.0...9.r..F..N.
00000b0: 40eb 0bb4 02e8 8500 3c0d 74ee 2c31 3c05  @.......<.t.,1<.
00000c0: 7502 cd18 73c4 980f a346 1073 bd88 46b5  u...s....F.s..F.
00000d0: 89ee 8a14 89f3 3c04 9c74 0ac0 e004 05be  ......<..t......
00000e0: 0793 c607 8053 f646 b740 7508 bb00 06b4  .....S.F.@u.....
00000f0: 03e8 5000 5e9d 7506 8a56 b480 ea30 bb00  ..P.^.u..V...0..
0000100: 7cb4 02e8 3e00 7282 81bf fe01 55aa 0f85  |...>.r.....U...
0000110: 78ff 56e8 1200 5eff e30f ab56 10be 8007  x.V...^....V....
0000120: e80a 0089 fee8 0c00 be82 07eb 07b0 3100  ..............1.
0000130: d0e8 0700 aca8 8074 f824 7fb4 0152 31d2  .......t.$...R1.
0000140: cd14 5ac3 8a74 018b 4c02 b001 5689 e784  ..Z..t..L...V...
0000150: d274 19f6 46b7 8074 1366 6a00 66ff 7408  .t..F..t.fj.f.t.
0000160: 0653 6a01 6a10 89e6 4880 cc40 cd13 89fc  .Sj.j...H..@....
0000170: 5ec3 0a46 3620 5058 450d 0a42 6f6f 743a  ^..F6 PXE..Boot:
0000180: 20a0 0d8a 83a5 a6a9 0607 0b0c 1013 1205   ...............
0000190: 0403 01bf 5769 ee4c 696e 75f8 7066 5365  ....Wi.Linu.pfSe
00001a0: 6e73 e590 9090 9090 9090 9090 9090 4472  ns............Dr
00001b0: 6976 6520 0000 8083 9090 9090 b600 8001  ive ............
00001c0: 0100 a50f ff92 3f00 0000 9112 0e00 0001  ......?.........
00001d0: c193 a50f ff25 0f13 0e00 9112 0e00 0000  .....%..........
00001e0: c126 a50f ff8b a025 1c00 a091 0100 0000  .&.....%........
00001f0: 0000 0000 0000 0000 0000 0000 0000 55aa  ..............U.
[/code]

So I figure I could probably mess around with these MBRs and re-image the cards as necessary... Only problem is, I don't know what each "partition" is for pfSense. There really only appears to be 1 "real" partition in IPSO, so I would like to try to replicate that with the pfSense MBR.

Can anyone point me to any kind of documentation as to what the "partitions" are in pfSense?

Any pointers on how to move forward with this?