Linked by Thom Holwerda on Wed 20th Jan 2010 22:45 UTC, submitted by kragil
Windows I guess it's Windows-flaw-week or something. First, we had the Internet Explorer vulnerability used in the Google attack, and now we have a bug that's been sitting undetected in Windows NT for 17 years. The bug can be used to escalate privileges, but from what I understand, it only works locally (although that isn't made clear).
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f0dder
Member since:
2009-08-05

AFAIK, it's a hardware issue. AMD dropped 16-bit PM operation in 64-bit mode.
Yep - that's another way to say "long mode doesn't support V86 tasks" ;)

The solution for Windows 7 is the fully-emulated VirtualPC copy of XP running in 32-bit mode. Ugly hack in a lot of ways, but it's part of the price to be paid for adopting amd64/x64.
Yeah, that'd work, but it's quite overkill for running 16bit DOS code... I'd start by trying my luck with http://www.dosbox.com/ , or perhaps even http://qemu.org/ .

If they were going to break backwards compatibility, they should have broken it good, and ditched the ability to make direct BIOS calls or boot 16-bit DOS at all.
Well, there's a few situations where you'll need it - the only one I know of, though, is the vanilla video driver that's used until you install a vendor specified driver. Also, the x86Bios*() functions are so limited that they can't really be used for much else...

But AMD probably doesn't have a license for EFI, and even if they had held one, Windows didn't support it. ;)
A shame, EFI is a nice idea in many ways... but was introduced far, far too late. Windows does have EFI support btw, at least Vista and onwards, but I dunno if it's generally available or you need a special version, and apparently it requires a bit of mucking about to install. But it's there ;)

FWIW, I'm really curious whether this might potentially affect other OSes that support 16-bit PM applications. OS/2 would be one of the first ones that might be worth looking at.
Other OSes are going to implement their "V86 monitor" differently - but it's probably a good bet that V86 monitor code hasn't been touch for several years for the OSes that include it, so it might be interesting to snoop around ;)

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