Linked by Thom Holwerda on Wed 18th May 2011 21:50 UTC, submitted by fran
Thread beginning with comment 473676
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RE: Intel cutting off some old instruction too?
by Neolander on Thu 19th May 2011 12:21
in reply to "Intel cutting off some old instruction too?"
Wouldn't be nice for Intel to start cutting off some old, unsupported instructions and enhance greatly x86 with this news version of Windows. I mean, if Windows 8 is breaking backward compatibility by requiring a Windows 7 layer, that layer could support some kind of emulation on the new chips. Dropping real mode and old, unused instructions could free up some nice space on the sillicon.
Take that with a grain of salt, but I think I've read somewhere that on modern x86 chips, real mode is emulated anyway, so you'd only save some kB of ROM.
Plus, you still need real mode for some fairly useful BIOS instructions and extensions.
Edited 2011-05-19 12:31 UTC
RE[2]: Intel cutting off some old instruction too?
by toast88 on Fri 20th May 2011 00:22
in reply to "RE: Intel cutting off some old instruction too?"
Take that with a grain of salt, but I think I've read somewhere that on modern x86 chips, real mode is emulated anyway, so you'd only save some kB of ROM.
I guess you are talking about the "Virtual 8086 mode"?
http://en.wikipedia.org/wiki/Virtual_8086_mode
This is not the real "real mode" but a virtual real mode on top of protected mode. The real "real mode" still exists native on any x86 CPU and it actually takes a reset cycle to get from protected mode back into real mode =).
If you want to know the details (and got the time), I recommend the programmer's handbook for the 386, which covers everything you need to know about x86 processors.
Linux Torvalds mentions somewhere in the early kernel sources that he read this manual as well besides to Tanenbaum's famous book on operating systems, of course.
Adrian





Member since:
2005-09-15
Wouldn't be nice for Intel to start cutting off some old, unsupported instructions and enhance greatly x86 with this news version of Windows. I mean, if Windows 8 is breaking backward compatibility by requiring a Windows 7 layer, that layer could support some kind of emulation on the new chips. Dropping real mode and old, unused instructions could free up some nice space on the sillicon.