[SeaBIOS] Bug#678042: seabios - Please enable Xen support

[Ian Campbell]

On Wed, 2012-06-27 at 11:55 +0100, Ian Campbell wrote:
> On Mon, 2012-06-25 at 18:55 -0400, Kevin O'Connor wrote:
> > On Wed, Jun 20, 2012 at 10:25:13AM +0100, Ian Campbell wrote:
> > > On Wed, 2012-06-20 at 10:22 +0100, Ian Campbell wrote:
> > > > Subject: [PATCH] enable Xen support by default.
> > > 
> > > In this context I thought it would also be useful to make
> > > CONFIG_DEBUG_IO_PORT dynamic. However with the below I get lots of build
> > > errors about xen_cpuid_base not being defined. I got similar errors
> > > without the VAR16VISIBLE and GET_GLOBAL hunks. I suspect this is due to
> > > the variable being used in both 32 and 16 bit mode and my not knowing
> > > what I'm doing in that regard ;-)
> > 
> > xen_cpuid_base is defined in xen.c which is only compiled in 32bit
> > mode, so you can't declare a variable as VAR16VISIBLE there.
> 
> Ah, right yes, thanks! I think I keep tripping over that...
> 
> > I wonder if it is simpler to define a "u16 DebugOutputPort
> > VAR16VISIBLE = CONFIG_DEBUG_IO_PORT" in output.c and then override it
> > early in the xen boot sequence though.
> 
> Yes, this makes sense. I actually went one further and nuked the Kconfig
> option, since it's only real non-default use was Xen. So now I makde it
> default to 0x402 and set it to 0xe9 in the Xen case.

Forgot to say that with d51c4a0df1ae7bcb20ec3d569e409cf50f3ed760 + 
 Xen: add definition of xen_hypercall_pa
 Xen: Autodetect debug I/O port at runti
 enable Xen support by default.

(first one sent to the list just now, other two in this thread).

SeaBIOS using a config derived from xen/tools/firmware/seabios-config
(which is the 1.6.x based config we use) works for me while a config
from "make defconfig" does not. I will investigate further.

Ian.