Date: Thu, 24 Feb 2000 12:07:11 +0200 (IST) From: Eli Zaretskii X-Sender: eliz AT is To: Chris Jones cc: djgpp AT delorie DOT com Subject: Re: Win 2000 & Djgpp In-Reply-To: <88udgt$74r$1@spruce.ukc.ac.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Reply-To: djgpp AT delorie DOT com Errors-To: dj-admin AT delorie DOT com X-Mailing-List: djgpp AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On Tue, 22 Feb 2000, Chris Jones wrote: > But what I can't understand is when Win32 > programs crash Windows 9x completely - surely they are insulated much more > than DOS apps, and shouldn't be able to do any damage at all. Actually, it's the other way around: DOS apps are insulated from the OS and from each other much more than Win32 apps. That's because DOS apps run in a different virtual machine (one each for every DOS box you have open on your system), while Win32 apps all run in the same VM, and share that VM with the kernel. The extra level of insulation between different VMs is due to several factors: - the description tables (LDTs) are not shared between VMs; - each VM uses a separate page directory. In contrast, different Win32 apps running in system VM all share the same LDT and the same page directory, the only insulation between them being the page tables, which Windows switches when it multitasks between Win32 apps.