CC'ing the mailing list. On Mon, May 23, 2011 at 03:24:05PM +0900, Daniel Castro wrote: > Kevin, > thanks for your answer. > > Please see below: > > On Sat, May 21, 2011 at 10:29 PM, Kevin O'Connor <[email protected]> wrote: > > On Thu, May 19, 2011 at 02:33:52PM +0900, Daniel Castro wrote: > >> Good Day, > >> > >> 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? > > > > In the general case, no. > > > > The ACPI spec does define a mechanism for the OS to inform the BIOS > > that it is transitioning from "Legacy state" to "Working state" via an > > SMI. SeaBIOS does have code for this (see src/smm.c), but it doesn't > > currently do anything interesting. Unfortunately, this is only > > available for OSs that support ACPI. > > In your opinion how hard would implementing that functionality will > be?
Well, there's code there today. Unfortunately it's all in 16bit mode assembler. If anything significant needs to be done then transitioning to C code would be needed, and getting that all setup would likely be a pain. >and how often that call is supported by HVM guests? Windows > support such feature? I think it's common for OSes to do this. It's been in the ACPI spec for some time, and not doing it would likely break USB keyboard emulation. -Kevin > > > > >> 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. > > > > Is it required to close the channel? Can opening a new channel > > implicitly close the old channel (I believe this is what the virtio > > stuff does)? > > > > -Kevin > > > > > > -- > +-=====---------------------------+ > | +---------------------------------+ | This space intentionally blank > for notetaking. > | | | Daniel Castro, | > | | | Consultant/Programmer.| > | | | U Andes | > +-------------------------------------+ _______________________________________________ SeaBIOS mailing list [email protected] http://www.seabios.org/mailman/listinfo/seabios
