Re: App database, libsynth

Bart Oldeman
2003-07-12T20:57:05Z

On Fri, 11 Jul 2003, Ryan Underwood wrote:

> On Fri, Jul 11, 2003 at 09:23:32PM +0100, Bart Oldeman wrote:
>
> > I was wondering btw:
> >
> > http://www.happypenguin.org/show?DOSbox
> > http://www.happypenguin.org/show?DOSbox&start=10
>
> "A DOS emulator that has exceeded dosemu."

it almost seems this comes from harekiet himself. But it's just a fanboy.
Anyway. I wish them good luck with DPMI.

> > One interesting platform is AMD's x86-64 (hammer, opteron, or whatever
> > it's called today). Linux for x86-64 does have modify_ldt but no v86.
> > That means that a potential future DOSEMU for it has to run "real
> > mode" 16bit apps emulated but can execute DPMI apps natively.
>
> Are you certain about emulation necessary for 16bit apps? I look at the
> developer's overview for hammer, and it starts out with:
>
> "The x86-64 architecture supports legacy 16-bit and 32-bit applications
> and operating systems without modification."

look carefully. x86-64 has three modes (instead of the familiar real
and protected modes) that can only be (normally) switched between
by rebooting:
real -- legacy -- long
16bit 32bit pm 64bit pm
16bit pm 32bit pm (compatibility)
vm86 16bit pm (compatibility)

dosemu runs in legacy mode but then your x86-64 is just an Athlon on
steroids and other processes cannot use more than 4GB of memory.

In long mode there is no vm86.

> To be honest, I think we can do everything Dosbox does as well. It is
> good to have both projects around though, because Dosbox presents more
> of a "zero-configuration" environment to the user, where DOSEMU has many
> more features that interact in various ways, so the user has to do some
> tweaking most of the time to get it working the way they want.

DOSEMU is intrinsically a little more difficult to configure (primarily
because it needs an independent DOS rather than having one built in) and
no matter how good FreeDOS gets it seems there will always be some who
really want to run another DOS in it. At least xdosemu+freedos should be
as easy as possible (it's been easy since 1.0.2, it's just that extracting two
tarballs in one's home directory is a little unusual -- that's why I tried
to simplify the systemwide compilation and installation from source, so
making RPMs and DEBs should be easy)

Bart