Subject: ffs on vnd on file on mfs mounted on ramdisk root
To: None <>
From: None <>
List: current-users
Date: 01/10/1999 01:32:45

I've been toying with the install system on i386 systems.  What I
wanted to do was to create a minimal ramdisk inside the kernel on
the boot diskette, and that this ramdisk image only contained the
bare minimum so that it could

a) mount an mfs file system of suitable size, on e.g. /mfs

b) copy the "traditional" ramdisk image from an external media to
   a file on /mfs, say /mfs/rd.fs

c) point a vnode device at /mfs/rd.fs

d) mount the vnode device at e.g. /ramdisk

e) chroot to /ramdisk (at which point I'm "in business", I hope).

I "met the wall" at point c) above; vnconfig hangs in biowait and
cannot be killed.  This may be due to a bug or a feature of the vnd
device driver (or it might be a problem of the underlying mfs file
system, although it could be written to just fine), and I'm not
certain which.  Since the whole VFS goo is like black magic to me,
I'm sort of stuck at this point.

I turned on VNDDEBUG and set vnddebug to 0xf with DDB in the running
kernel before the vnconfig step was done, and this resulted in the
following output before it hung:

vndopen(0xe03, 0x3, 0x6000, 0xf29c9738)
vndioctl(0xe03, 0xc01c4600, 0xf29e2ec8, 0x3, 0xf29c9738)
vndioctl: SET vp 0xf29e909c size 0x800 512/32/64/1
vndstrategy(0xf0f7491c): unit 0
vndstrategy: vp 0xf29e909c/0xf29c5ea0 bn 0x0/0x70 sz 0x200
vndstart(0): vp 0xf0575000 vp 0xf29c5ea0 blkno 0x70 addr 0xf1da8000 cnt 0x200
vndiodone(0): vbp 0xf0575000 vp 0xf29c5ea0 blkno 0x70 addr 0xf1da8000 cnt 0x200

Any information and assistance would be greatly appreciated, even
if it is "sorry, can't be fixed due to xxx".


- H=E5vard