On 19.05.11 at 07:33, Daniel Castro evil.dani@gmail.com wrote:
In order to give PV Drivers to SeaBIOS we will need to solve a few problems, one is the following: Does a booting kernel informs the BIOS that it will leave real mode and not use it again? When the booting kernel uses CPU real mode for the last time, how can we (Xen or SeaBIOS) know that real mode will
no
longer be used, and hence BIOS calls will not be issued? We want upon last real mode usage to leave all Xen PV information in
a
clean state, this means, closing the channel and ring between the newly created domain and the host system.
How can you be certain an OS won't switch back to real mode even after an extended period of up-time? Or that such switching back would affect you (could be calling e.g. the video or PCI BIOS functions only).
Well that's a problem with any device with a real mode counterpart (eg INT13 for storage) isn't it? so just handle it in the same way.
James