4 ms·

Dosemu2: a re-incarnation of Dosemu

16 points by galapago 11y ago

atesti 11y ago
Was development of the original dosemu stopped?
skrowl 11y ago
I'm not familiar with dosemu. How does it compare to dosbox, or just installing dos on VirtualBox / etc? Also, it appears to be 6 months since the last release of dosemu2. Is it already abandoned?
- dfox 11y ago
  Dosbox does CPU emulation and all full-machine virtualization solutions have to do the same for real mode code. Original dosemu on the other hand works in mostly same way as DOS window/NTVDM in Windows/Windows NT. i386 has support for essentially transparent switches between 16/32bit protected modes and special mode in which it runs plain real mode code but paging is active and privileged operations cause traps into kernel/hypervisor (then usually called "VM manager" or such) these two features are designed to support exactly this kind of backward-compatibility layers and were used both for multitasking of DOS software (Windows, OS/2, DESQview, ...) as well as to extend capabilities of DOS itself (various mechanisms for accessing more than 640KB RAM from real mode, DOS extenders, DPMI servers, hardware compatibility layers (which did not work so well)). Most DOS software does not do anything that cannot be emulated by combination of these two mechanisms and programs that do such things are almost universally DOS based loaders for another operating systems. Problem with this whole thing is that this does not work on x86_64 with 64bit kernel. (another thing is that any implementation of this mechanism is invariably one big colossal mess of edge cases and ugly hacks, but it does work and surprisingly reliably)
  - Zardoz84 11y ago
    > Problem with this whole thing is that this does not work on x86_64 with 64bit kernel. Shit!
  - Chuck_G 11y ago
    Well, yes it does, at least on Ubuntu x64. (I'm using it now). See: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1328965 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1328965
dimitar 11y ago
I remember using dosemu for some gamesabout 15 years ago on a slow computer. It was much faster than dosbox. Nowadays it doesn't seem to matter. It was also really easy to setup.

16 points by galapago 11y ago

Was development of the original dosemu stopped?

I'm not familiar with dosemu. How does it compare to dosbox, or just installing dos on VirtualBox / etc? Also, it appears to be 6 months since the last release of dosemu2. Is it already abandoned?

dfox 11y ago
Dosbox does CPU emulation and all full-machine virtualization solutions have to do the same for real mode code. Original dosemu on the other hand works in mostly same way as DOS window/NTVDM in Windows/Windows NT. i386 has support for essentially transparent switches between 16/32bit protected modes and special mode in which it runs plain real mode code but paging is active and privileged operations cause traps into kernel/hypervisor (then usually called "VM manager" or such) these two features are designed to support exactly this kind of backward-compatibility layers and were used both for multitasking of DOS software (Windows, OS/2, DESQview, ...) as well as to extend capabilities of DOS itself (various mechanisms for accessing more than 640KB RAM from real mode, DOS extenders, DPMI servers, hardware compatibility layers (which did not work so well)). Most DOS software does not do anything that cannot be emulated by combination of these two mechanisms and programs that do such things are almost universally DOS based loaders for another operating systems. Problem with this whole thing is that this does not work on x86_64 with 64bit kernel. (another thing is that any implementation of this mechanism is invariably one big colossal mess of edge cases and ugly hacks, but it does work and surprisingly reliably)
- Zardoz84 11y ago
  > Problem with this whole thing is that this does not work on x86_64 with 64bit kernel. Shit!
- Chuck_G 11y ago
  Well, yes it does, at least on Ubuntu x64. (I'm using it now). See: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1328965 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1328965

dimitar 11y ago

I remember using dosemu for some gamesabout 15 years ago on a slow computer. It was much faster than dosbox. Nowadays it doesn't seem to matter. It was also really easy to setup.