Messages in this thread | | | Subject | Re: [Lguest] lguest: unhandled trap | From | Ian Campbell <> | Date | Mon, 20 Oct 2008 10:14:15 +0100 |
| |
On Mon, 2008-10-20 at 09:53 +0200, Ingo Molnar wrote: > * Jeremy Fitzhardinge <jeremy@goop.org> wrote: > > > Ingo Molnar wrote: > >> i think Xen can withstand DMI scanning just fine. > >> > >> without having seen any background, my general feeling is that lguest > >> should either do what Xen does and reserve the classic BIOS ranges > >> that we probe - or we should make DMI scanning more robust by making > >> sure real RAM ranges are never probed. (only ranges that the BIOS > >> itself marks as reserved in the e820 map) > > > > We considered doing that, but decided that there was so many other > > pieces of code around the place that assume that the ISA area is > > special, that just reserving it was the best course of action. > > yeah - for _any_ virtual machine environment it's beneficial to look as > much like a normal PC as possible, because normal PCs is where the code > gets tested most. > > Nevertheless if this is the only current roadblock for lguest then i > wouldnt find it objectionable to make DMI scanning more robust that way > - the two are complimentary. [ With an initial transitionary period of > generating printks and WARN()s when we try to scan general RAM areas. ]
Wasn't there some concern about BIOSes which don't correctly reserve their DMI tables? Or don't even have e820 maps? H. Peter once said:
> It's pretty standard for 0xf0000...0x100000 to be marked RESERVED in > E820 on real hardware (including the system I'm typing on right now.) > It is so marked to indicate that hardware cannot be mapped into that > space. However, you can't rely on this fact -- heck, you can't rely on > E820 even existing on a real machine. I have specimens of real-life > machines that go both ways.
Ian.
| |