Gleb Natapov wrote: > On Mon, Nov 23, 2009 at 10:30:56PM +0100, Sebastian Herbszt wrote: > > Gleb Natapov wrote: > > >On Mon, Nov 23, 2009 at 08:19:54PM +0100, Sebastian Herbszt wrote: > > >>Gleb Natapov wrote: > > >>>On Sun, Nov 22, 2009 at 09:01:45PM +0100, Sebastian Herbszt wrote: > > >>>>Gleb Natapov wrote: > > >>>>>On Sun, Nov 22, 2009 at 04:31:24PM +0100, Sebastian Herbszt wrote: > > >>>>>> > > >>>>>>Bad things could happen if someone modifies the BIOS because it's > > >>>>>>unprotected > > >>>>>>(e.g. VM crash). > > >>>>>> > > >>>>>BIOS is reloaded during VM reset. > > >>>> > > >>>>The BIOS is not reloaded - tested with "reboot" on Linux and > > >>>>system_reset in monitor. > > >>>> > > >>>Looks like a bug. Tested with latest QEMU version I assume? > > >> > > >>Tested with v0.11.0-rc0-1677-gf165b53. Where do you suspect a bug? In the > > >>behaviour > > >>on "reboot" or system_reset? I think it depends wheter it's a software or > > >>hardware reset. > > >> > > >The bug is that BIOS rom is not reloaded on hardware reset (what do you > > >call software reset?). Can you retest with latest git? > > > > Same with v0.11.0-rc0-1699-gb0293e5. > > Bochs has the notion of BX_RESET_SOFTWARE and BX_RESET_HARDWARE. Those > > two describe the source of the reset and the hardware, in most cases just > > the cpu, is reset > > differently depending on the source (e.g. hardware reset / power on vs. > > INIT#). I think this > > behaviour is also described in the 440fx spec (chapter "4.5.3 SYSTEM > > RESET"). > > > > If the monitor command "system_reset" is supposed to be the equivalent of > > pushing the reset > > button of the box, then the bios should be reloaded (i think, not entirely > > sure what the pin is > > wired to). But the bios should not be reloaded if the OS just jumps to the > > bios reset code. > > > Correct, but modern OSes never jump to the bios reset code. They use > ACPI reset, kbd reset or triple fault to do reset. All of those generate > exactly the same kind of reset as "system_reset" monitor command.
Modern OSes don't (though Linux still has the option reboot=bios which jumps to the BIOS reset code, because that's needed on some PCs!). But QEMU is used to run old OSes too. -- Jamie
