albert.wik
New Member
Hi all,
From what I could find, there is no description on the Internet about how to mount a Xenix (System V) file system, so I thought I should document it, before I forget it.
First, on Linux, let's switch to the root user:
The Xenix file system is contained in an image file called "286.img". It seems reasonable to try to mount it as follows, by using the Linux loop device facility:
That failed. Now let's see if the loop device (backed by the file "286.img") has any partitions. It turns out there's a primary partition number 4:
That looks promising! Let's try mounting it:
Failure again. So let's get "clever"! Booting into Xenix with QEMU:
In Xenix:
Take note of the characters in bold-italic above. As you'll see, you will need them further on.
Back to Linux:
So, apparently, the Xenix root file system starts at offset 0xfc000 into the image file.
Armed with that fact, let's try setting up the loop device again:
Let's try mounting it:
Finally success!
Regards,
Albert.
From what I could find, there is no description on the Internet about how to mount a Xenix (System V) file system, so I thought I should document it, before I forget it.
First, on Linux, let's switch to the root user:
Code:
$ su
Password:
#The Xenix file system is contained in an image file called "286.img". It seems reasonable to try to mount it as follows, by using the Linux loop device facility:
Code:
# ls -l 286.img
-rw-r--r-- 1 aw aw 541065216 Jul 10 08:53 286.img
# losetup /dev/loop0 286.img
# mount -t sysv -r /dev/loop0 /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.That failed. Now let's see if the loop device (backed by the file "286.img") has any partitions. It turns out there's a primary partition number 4:
Code:
# fdisk -l /dev/loop0
Disk /dev/loop0: 516 MiB, 541065216 bytes, 1056768 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe264e264
Device Boot Start End Sectors Size Id Type
/dev/loop0p4 * 63 1056383 1056321 515.8M 2 XENIX root
# ls -l /dev/loop0*
brw-rw---- 1 root disk 7, 0 Jul 10 08:32 /dev/loop0
brw-rw---- 1 root disk 259, 0 Jul 10 08:32 /dev/loop0p4That looks promising! Let's try mounting it:
Code:
# mount -t sysv -r /dev/loop0p4 /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop0p4, missing codepage or helper program, or other error.Failure again. So let's get "clever"! Booting into Xenix with QEMU:
Code:
# cat qemu.cmd
qemu-system-i386 -M isapc 286.img -k sv
# . ./qemu.cmdIn Xenix:
Code:
# mount
/dev/root on / read-write on Fri Jul 11 08:39:01 2020
# dd if=/dev/root | hd | head -2
0000 [B][I]c7 74 3a 26[/I][/B] 8a 05 0a c0 74 33 36 89 3e 0e 06 38 .t:&....t36.>..8
0010 c8 75 1c 47 51 56 50 ac e8 1e f4 ae 75 0e e2 f7 .u.GQVP.....u...
# shutdown 0Take note of the characters in bold-italic above. As you'll see, you will need them further on.
Back to Linux:
Code:
# hexdump -C 286.img | grep c7.74.3a.26
000fc000 c7 74 3a 26 8a 05 0a c0 74 33 36 89 3e 0e 06 38 |.t:&....t36.>..8|
^CSo, apparently, the Xenix root file system starts at offset 0xfc000 into the image file.
Armed with that fact, let's try setting up the loop device again:
Code:
# losetup -d /dev/loop0
# losetup /dev/loop0 286.img -o 0xfc000Let's try mounting it:
Code:
# mount -t sysv -r /dev/loop0 /mnt
# ls -l /mnt
total 28
...
-rw-r--r-- 1 sys sys 287702 Jun 12 1989 xenixFinally success!
Regards,
Albert.
