re: Re: Dosemu

On 10 Nov 2002 [email protected] wrote:

> El dom, 10-11-2002 a las 20:24, Bart Oldeman escribi=F3:
> > On Mon, 11 Nov 2002, Eric Auer wrote:
> ...
> >
> > Debian, Gentoo, PLD (a Polish distro) and ALT Linux (a Russian
> > distro) have DOSEMU too. Red Hat doesn't have it anymore. I don't know
> ...
>
> Yes, Debian's Gnome-Desktop has it on the "Debian Menu"->Apps->Emulators
>
> However, when you install dosemu, it tells you, that FreeDos cannot be
> delivered with Dosemu, since it does not comply with Debian
> requirements, I suppose Copyright Policies.

Nobody so far has bothered to package the source code of
dosemu-freedos-bin.tgz in a convenient .deb, that's the reason.
Once that's done it can go into 'contrib', so it still wouldn't be in
'main' i.e. it's left out on many Debian CDs.

DOSEMU in Debian is in a somewhat peculiar situation. It is not in 'main'
since it cannot run standalone (without a DOS available). And FreeDOS
cannot be in Debian 'main' because it cannot be compiled using Free
compilers (for anything in 'main' you are able to download and compile
the source using compilers and tools that are part of 'main').

> You have to follow instructions in a file named
> /usr/share/doc/dosemu/README.Debian to do this, where the only problem
> is, that the given ftp-address for dosemu-freedos-bin.tgz is incorrect.

right ftp.dosemu.org is permanently down. You can file this as a
documentation bug to the Debian people if you like.

> Given a correctly downloaded dosemu-freedos-bin.tgz (from sourceforge,
> for example) all other steps get you immediatly to a running Freedos
> under Debian.  Just tested it out.

yes.

> I do not use the virtual packet driver, so I cannot say anything about
> it, but the second question has to be answered with a definitly yes!

the packet driver works but is quite limited. if you just want to share
files and printers you don't need it.

> There are major compatiblity differencies.
>
> If FreeDos is run standalone, it has direct access to the computers
> hardware.  Dosemu, while beeing a great product, uses emulation for some
> hardware functions and "wrappers" for others.  As this is Software, it
> contains bugs, and there is no guarantee that it works the same way.
> On the other hand, there are issues of the underlying operating system
> (unix), which deal either with security, or with adaptation to its way
> how hardware is dealt with, which make dosemu behave diferent than a
> mere '86 hardware, no matter if you run FreeDos or MS-Dos, or any other
> Dos.

Essentially, for the DOS kernel itself it doesn't make much of a
difference since it lives on top of the BIOS and not so much the hardware.
With a hard disk image you also get exactly the same filesystem behaviour.
However for programs that directly access the hardware it can make a huge
difference; this of course depends on the hardware.

Programs like UMBPCI and EMM386 cannot work in DOSEMU, for instance.

> On the other hand, you are provided with a "shield" against
> malfunctioning programs.  If a FreeDos (or any other) crashes, you just
> kill the emulator job, no harm is done to the operating system.  There
> are many debugging options, which allow you to "X-Ray" the running
> FreeDos kernel and applications when you use dosemu.

Yep, and that makes it quite handy for testing and debugging -- without
DOSEMU (and dosdebug) I would be nowhere in developing the kernel.

Bart