Now this reminds me of “turning the engine off and then back on again at 55 mph.”

the v86-64 patch, Allows you to enter v86 mode from long mode on a 64bit linux kernel.

Basically it works just like an old school DOS Extender, where it’ll switch from long mode, to 32bit compatible mode, then enter v86 mode run some code, then re-enter 32bit mode, to jump back into 64bit long mode.

From an old mailing list:

PERFORMANCE
This 64-bit DOSEMU compile runs substantially slower than the 32-bit compile
that I used previously on this computer.  I have several rather large
<a href="http://www.powerbasic.com/products/pbdos/">PowerBASIC/DOS</a> programs that are, in fact, the main reason why I use DOSEMU.

Up until a couple of days ago, I had Fedora 7/i386 on this computer.  I just
happen to still have the numbers when compiling one of those programs with
PowerBASIC/DOS under DOSEMU:

With F7/i386:  1686600 lines per minute -- total time to compile the program:
0.2 seconds

With F8/x86_64:  230400 lines per minute -- total time to compile the program:
1.6 seconds.

The F8/x86_64 DOSEMU is running approximately 13 times slower.

Which I bet runs a bit faster than an old 386.

This entry was posted in 64bit computing, Linux, v86, x64, x86_64 by neozeed. Bookmark the permalink.
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About neozeed

What is there to tell? I’ve loved UNIX like things since I was first exposed to QNX in highschool (we had the Unisys ICONS!), and spent the better time of my teenage years trying to get my own UNIX… I should have bought Coherent in retrospect.. Anyways latched onto Linux in 1992, and then got some old BSD admin books and have been hooked on the VAX BSD & other big/ancient things since…!

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