Re: [PATCH v2] x86/vm86: Remove deprecated VM86 support

[Jari Ruusu]

Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> I'm really curious what software this is and what kind
> of performance boost you see.
 
I am more or less "stuck" with old DOS version of WordPerfect
for opening/editing/saving/printing some really old long-term
industrial project documentations that were originally created
more than 30 years ago. All attempts to open such files with
other tools will always result in complete mess. Choices are:
(1) re-do all those old project documentations with some other 
tool, or (2) start old DOS version of WordPerfect.
 
With CONFIG_X86_LEGACY_VM86=y set in 32-bit Linux kernel,
currently running linux-6.12.91, one memory+CPU intensive
operation in DOS version of WordPerfect takes less than 0.5
seconds. With CONFIG_X86_LEGACY_VM86 not set, same operation
takes about 2 seconds.
 
> I'm also curious why modern virtualization hardware
> doesn't help either.
 
My current setup uses virtualization:
 
64-bit x86 host + 64-bit Linux kernel/distro + Qemu/KVM               
  --> boots 32-bit Linux kernel/distro ( X86_LEGACY_VM86=y )
    --> boots dosemu + FreeDOS
      --> runs DOS version of WordPerfect

--
Jari Ruusu  4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD  ACDF F073 3C80 8132 F189