On Sat, Mar 20, 2010 at 3:18 PM, Avi Kivity <avi@xxxxxxxxxx> wrote: > On 03/20/2010 10:55 AM, Alexander Graf wrote: >>> >>>> I'd say that a GSoC project would rather focus on making a guest OS work >>>> than working on generic big real mode. Having Windows 98 support is way more >>>> visible to the users. And hopefully more fun to implement too, as it's a >>>> visible goal :-). >>>> >>>> >>> >>> Big real mode allows you to boot various OSes, such as that old >>> Ubuntu/SuSE boot loader which triggered the whole thing. >>> >> >> I thought legacy Windows uses it too? >> > > IIRC even current Windows (last I checked was XP, but it's probably true for > newer) invokes big real mode inadvertently. All it takes is not to clear fs > and gs while switching to real mode. It works because the real mode code > never uses gs and fs (i.e. while we are technically in big real mode, the > guest never relies on this), and because there are enough hacks in vmx.c to > make it work (restoring fs and gs after the switch back). IIRC there are > other cases of invalid guest state that we hack into place during mode > switches. > >> Either way - then we should make the goal of the project to support those >> old boot loaders. IMHO it should contain visibility. Doing theoretical stuff >> is just less fun for all parties. Or does that stuff work already? >> > > Mostly those old guests aged beyond usefulness. They are still broken, but > nobody installs new images. Old images installed via workarounds work. > > Goals for this task could include: > > - get those older guests working > - get emulate_invalid_guest_state=1 to work on all supported guests > - switch to emulate_invalid_guest_state=1 as the default > - drop the code supporting emulate_invalid_guest_state=0 eventually To this end I guess the next logical step is to compile a list of guests that are currently not working/work with hacks only, and get them working. Here are some suggestions: - MINIX 3.1.6 (developers have been recently filing bug reports because of boot failures) - Win XP with emulation enabled - FreeDOS with memory extenders Any other guests you'd like to see on this list? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
