[9fans] Weird plan9 Xen DonU problems

["Alan C. Fisher" <acf@unixcube.org>]

When running the plan9 installer in Xen, partdisk fails strangely:

init: starting /bin/rc
/bin/dossrv: serving #s/dos
dev 3 sector 18, write: 0, should be 4608
dev 3 sector 0, write: 0, should be 4608
dev 3 sector 18, write: 0, should be 4608
dev 3 sector 9, write: 0, should be 4608
dev 3 sector 4248, write: 0, should be 4608
use DMA for ide drives[yes]: no
rio: can't open display: initdisplay: /dev/draw/new: unknown device in # filename


failed to start rio.  you can start a text-based installation by running

	inst/textonly


init: starting /bin/rc
% inst/textonly
Sun Oct 2 02:16:21 BST 2011 Installation process started

--------------------------------------

Preparing menu...
The following unfinished tasks are ready to be done:
	configfs	- choose the type of file system to install
	stop	- save the current installation state, to be resumed later

Task to do [configfs]:

--------------------------------------
You can install the following types of file systems:

	fossil			the new Plan9 fileserver
	fossil+venti	fossil + a archival dump server

File system (fossil, fossil+venti)[fossil]:

--------------------------------------

Preparing menu...
The following tasks are done:
	configfs	- choose the type of file system to install

The following unfinished tasks are ready to be done:
	partdisk	- edit partition tables (e.g., to create a plan 9 partition)
	stop	- save the current installation state, to be resumed later

Task to do [partdisk]:

--------------------------------------
The following disk devices were found.

sd00 - Xen block device

sd01 - Xen block device

Disk to partition (sd00, sd01)[no default]: sd00
The disk you selected HAS NO master boot record on its first sector.
(Perhaps it is a completely blank disk.)
You need a master boot record to use the disk.
Should we install a default master boot record?

Install mbr (y, n)[no default]: y
mbr: reading boot sector: './disk' file does not exist

This is disk/fdisk; use it to create a Plan 9 partition.
If there is enough room, a Plan 9 partition will be
suggested; you can probably just type 'w' and then 'q'.

/bin/disk/fdisk: diskread 68 at 0.446: './disk' file does not exist

--------------------------------------

Preparing menu...
The following tasks are done:
	configfs	- choose the type of file system to install

The following unfinished tasks are ready to be done:
	partdisk	- edit partition tables (e.g., to create a plan 9 partition)
	stop	- save the current installation state, to be resumed later

Task to do [partdisk]: mercury# ls

Note the lines:
mbr: reading boot sector: './disk' file does not exist
and
/bin/disk/fdisk: diskread 68 at 0.446: './disk' file does not exist

I have made sure that DMA is off, and that the disk is writeable in the Xen config file.

This was tested with "plan9.iso" from http://plan9.bell-labs.com/plan9/download.html, as well as 9atom.

Here are some useful bits of information:

If I run "disk/fdisk -a /dev/sd00/data" in rc, I get the same response:
/bin/disk/fdisk: diskread 68 at 0.446: './disk' file does not exist

% cat > /dev/sd00/data
hello, world
cat: write error copying <stdin>: './cat' file does not exist
%

When I specify the entire path to /bin/disk/fdisk, the "'./disk' file does not exist" part doesn't happen.
/bin/disk/fdisk: diskread 68 at 0.446:

echo asdfasdfsdf > /dev/sd00/data && cat /dev/sd00/data
returns nothing, ie, the disk doesn't seem to have been written to.

% cat /dev/sd00/ctl
inquiry Xen block device
geometry 2097152 512
part data 0 2097152

% ls -l /dev/sd00
--rw-r----- S 0 glenda glenda          0 Feb 11  2010 /dev/sd00/ctl
--rw-r----- S 0 glenda glenda 1073741824 Feb 11  2010 /dev/sd00/data
-lrw------- S 0 glenda glenda          0 Feb 11  2010 /dev/sd00/raw

Thank you very much to 'f2f' and 'lmnopqr' in #plan9 on freenode for their help in trying to figure this out.

Thanks,
Alan C. Fisher