[SeaBIOS] [PATCH v16] Add pvpanic device driver

Kevin O'Connor kevin at koconnor.net
Tue Apr 2 02:22:57 CEST 2013

On Sun, Mar 31, 2013 at 05:34:10PM +0300, Gleb Natapov wrote:
> On Sat, Mar 30, 2013 at 09:20:09AM -0400, Kevin O'Connor wrote:
> > On Fri, Mar 29, 2013 at 02:49:12PM +0100, Paolo Bonzini wrote:
> > > Il 29/03/2013 14:33, Kevin O'Connor ha scritto:
> > > > On Fri, Mar 29, 2013 at 04:18:44PM +0800, Hu Tao wrote:
> > > >> pvpanic device is used to notify host(qemu) when guest panic happens.
> > > > 
> > > > Thanks.  However, we're planning a move of ACPI tables from SeaBIOS to
> > > > QEMU.  I think this should wait until after the move.
> > > 
> > > The device should be in QEMU 1.5, and the SSDT probably will still be in
> > > SeaBIOS by then (and might even be the last to move, since it's quite
> > > complex and dynamic).  I don't think it is fair to block this patch on
> > > those grounds...
> > 
> > What is the user visible impact of not having a panic device?
> > 
> > My main concern is that the patch creates a new fw_cfg channel between
> > qemu and seabios thats sole purpose is to alter the OS visible ACPI
> > tables.  These types of QEMU->SeaBIOS interfaces are fragile and are
> > (in sum) quite complex.
> > 
> The patch uses existing channel between qemu and seabios, one
> romfile_loadint() is all it takes. We already have number of interfaces
> to change OS visible ACPI tables, that's why we want to move ACPI table
> creation to QEMU in the first place. It is unfortunate to start blocking
> features now before we have an alternative. When ACPI table creation
> will move into QEMU the code in this patch will be dropped along with
> all the other code that serves similar purpose.

Hi Gleb,

If there is a general consensus that this feature is important then
we'll go forward with adding it as is.  To be clear though, my
preference would be to go forward with moving ACPI tables into QEMU,
and then add this stuff on top of that.  If no one beats me to it,
I'll send some initial patches myself.

If we do merge this feature as is, it will also require a SeaBIOS
release (followed by a SeaBIOS pull into QEMU).  There weren't any
short-term plans for a new SeaBIOS release - if this feature demands
that then we need to start planning it now.


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