On Tue, Sep 30, 2014 at 7:22 PM, wch-t...@house-grp.net
<wch-t...@house-grp.net> wrote:
> I have a host machine (Dom0) running OpenSUSE xen kernel version
> 3.11.10-21.1.

I applaud you for trying such an emulator with FreeDOS. Even I don't
have the energy to try every emulator under the sun anymore.

> I am using the xl tool stack to the extent I can. I have installed freedos as 
> a guest.
> I am encountering errors such as
> "Error reading from drive C: DOS area: write-protection violation attempted
> (A)bort, (I)gnore, (R)etry, (F)ail?"

Probably unrelated, but I sometimes get a critical error when doing
tab completion under FreeCOM (0.84-pre2 XMS_Swap) with DOSLFN enabled.
I don't know the details, but I vaguely assumed it was because there
is no physical A: drive on this PC. I think I even get it with DOSEMU.

Maybe I'm totally wrong, but I never knew really how to debug or
isolate it, so I just ignored it. I'm no kernel guru, so I have no
idea. Maybe it's actually a shell (FreeCOM) bug. Obviously plugging in
a USB floppy drive (which I have) could maybe prove it (if the error
goes away), but I've never been that interested these days. (Which is
saying a lot because I care more about floppies than 99% of people.)

I know that's not directly helpful, but that's my first (naive) guess,
though probably wrong.

> immediately after boot but a C prompt eventually comes up after a few "A"s.
> I have an MSDos 6.22  vm which runs without complaint.

It could just be that MS-DOS ignores it entirely, i.e. silently fails.
Though more likely, you're correct, it's probably a rare FreeDOS bug.

You could try a different FreeDOS kernel (e.g. 2036 or 2038) and/or a
different shell (0.82pl3 or 4DOS). If it's still a bug, at least
you've confirmed that it's not unique to what you have now.


BTW, some emulators are just buggy. Most people, even developers,
don't seem to test very well except with a limited number of modern
OSes, usually Windows or Linux. So it's not true that it couldn't be
Xen's fault.

> The xl configuration files are almost identical.  Here is the freedos config
> file:
> boot = "cd"
> disk = [ "file:/v/v.../freedos_1.1_n01-hda.raw,hda,w",
> "file:/v/../freedos_1.1_src.iso,hdc:cdrom,r" ]

I'm not much help here. I don't know what any of this means. While I
am on Linux now, it's an old PuppyLinux (Lucid, aka 10.04 or such), so
I don't probably have a good way to install or build latest Xen to

Maybe someone else will chime in, so I'll put this link here:


> This is the type of error I would see on a damaged floppy drive or one with
> the write protection slot covered, or on a failing/failed C drive; but
> freedos installed on this image file without any trouble (after I got the
> order of operations right).

So this error is on every boot, after AUTOEXEC has finished running?

> If images are permitted, I can send a screen shot of the display.

Dunno about images being allowed. Probably better to host them
elsewhere and link to them indirectly.

> Since
>     1) I am running as root (and therefore should not encounter any
> permissions problems) and
>     2) MSDos runs without trouble and
>     3) freedos installed and is obviously running
> I am assuming xen is OK and that my configuration file is OK, but could I
> have a timing issue?
> Is the CPU too fast? ( I-7 @ 2200GHz)I have seen some notes which mentioned
> throttling back a cpu.  I tried caping the CPU at 20% which did not seem to
> help.

Dunno. It's probably not a timing issue, but I think FreeCOM does try
to do something weird for the internal BEEP command. So who knows,
anything's possible.

> If someone has some idea as to the cause of and cure for this behavior, I
> would like them to share it with me.

I don't hold much hope for getting much sympathy upstream, but if
you're courageous enough, you could visit their IRC and ask someone


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