On Sat, 20 Nov 2004 17:07:52 -0800 (PST), Harshal Vaidya <[EMAIL PROTECTED]> wrote: > Hi Saifi, > Thanks for a long and detailed explanation. Actually I > had already had a good understanding of the concept of > platform simulators. However nevermind you explained > it to me oce again. > > I don't want to sound pedantic but there you mentioned > that Bochs is an emulator. There is a suttle > difference which we need to understand here. > > An emulator makes an attempt to actually virtualize a > system (as far as possible) . For e.g. the clock tick > interrupt is never generated by the emulator s/w. > Instead the emulator just handles the underlying > hardwares clock tick interrupt and shows it as the > clock tick interrupt to the guest OS. > > On the contarary a simulator would actually generate a > clock tick interrupt via software. Hence simulators > always run a number of times slower than emulators. > > There are many more examples which can explain this > concept. Have a look at this link. > > http://www.kernelthread.com/publications/virtualization/ > > So, the conclusion is > Bochs is a simulator and > VMWare is a emulator. >
Greetings Harshal, I really appreciate that you took time to write down a detailed mail. You have raised a very interesting point and I am going to look at more closely the issues at hand. The link you sent is quite informative and I picked up on few things that I was not sure of. There is one thing in the paper that baffles me :-) The author says "Bochs is an open-source x86 emulator written in C++ .... ... highly portable and rather slow (not surprising since it emulates every instruction and I/O devices)" That is the general impression! However, you have highlighted the "host-guest" relationship in the context of clock interrupts. Wow, thats pretty interesting, since a good emulator would always need to *simulate* the *missing device* (in some cases) so to speak. Harshal, thanks for pointing that out. And, hey do keep writing such enlightening nuggets from time to time. Thanks and regards Saifi. -- ______________________________________________________________________ Pune GNU/Linux Users Group Mailing List: ([EMAIL PROTECTED]) List Information: http://plug.org.in/mailing-list/listinfo/plug-mail Send 'help' to [EMAIL PROTECTED] for mailing instructions.
