[SeaBIOS] [PATCH v2 00/19] SeaBIOS as Compatibility Support Module for UEFI/OVMF

[Ian Campbell]

On Fri, 2013-02-08 at 10:33 +0000, David Woodhouse wrote:
> On Fri, 2013-02-08 at 09:51 +0000, Ian Campbell wrote:
> > I've not been following this thread all that closely, what
> > specifically should I be testing on Xen? Just starting a guest which
> > uses pmtimer under latest SeaBIOS git and checking it works OK?
> 
> It's not merged yet; it's at http:// and
> git://git.infradead.org/users/dwmw2/seabios.git

Thanks I ran a build with this and I had to select between "Coreboot",
"Qemu" or "CSM". Xen depends on !Coreboot so I probably ought to select
the Qemu option but it seems like the Qemu option is misnamed, unless
there are other things under the Qemu umbrella perhaps "Virtualised
(Qemu or Xen)"?


> Specifically commit 5ba80fac ("Add find_pmtimer() function") and
> 56014611 ("Use find_pmtimer() after copying Xen ACPI tables").
> 
> Previously, SeaBIOS wouldn't use the pmtimer for its own timing purposes
> unless it actually set it up for itself and created its *own* ACPI
> tables.
> 
> I've made it look through the ACPI tables which are provided to it by
> Coreboot/Xen/CSM and *find* the pmtimer there, and use it.
> 
> So with debug enabled you should see a line something like
> 'Using pmtimer, ioport 0xb008, freq 3579 kHz' and then lots of
> 'pmtimer: 0:16408743' as it actually gets read, and the debug statement
> in pmtimer_get() gets invoked.

Running with your HEAD (1c78b74) I get:
XEN) HVM51: Invoking SeaBIOS ...
(XEN) io.c:201:d51 MMIO emulation failed @ 0008:ffff1474: 00 80 2d c0 c4 82 ff ff 18 7a
(XEN) hvm.c:1237:d51 Triple fault on VCPU0 - invoking HVM system reset.

I don't see this with rel-1.7.2. Bisecting fingers
        commit 6ca0460fbb8ecfa5d42c8928b7ee71f20d0cffdb
        Author: Kevin O'Connor <kevin at koconnor.net>
        Date:   Mon Jan 21 11:38:49 2013 -0500
        
            POST: Reorganize post entry and "preinit" functions.
        
But it doesn't look like this changes the order of anything, 

I'm not quite sure what address ffff1474 is, if it corresponds to
address f1474 in SeaBIOS then it corresponds to:
000f1474 <__make_bios_writable_intel>:
   f1474:       55                      push   %ebp
   f1475:       57                      push   %edi
   f1476:       56                      push   %esi
   f1477:       53                      push   %ebx
   f1478:       83 ec 0c                sub    $0xc,%esp
   f147b:       89 d3                   mov    %edx,%ebx
   f147d:       0f b7 e8                movzwl %ax,%ebp
   f1480:       c1 e5 08                shl    $0x8,%ebp

but that doesn't correspond to the instruction stream bytes in the emu
failed message, I also wouldn't expect a stack push to result in MMIO
but stranger things have happened ;-). Lastly that call seems to be
after the SeaBIOS banner should have been printed.

But, I can't find those bytes anywhere else in the objdump. 00 80 2d
seems to be an add of ax and [bx] + 0x2d

> And clock stuff should work correctly.

Clock stuff in SeaBIOS or in the eventual kernel?

Ian.

Logs, SeaBIOS starts after "Invoking SeaBIOS ..."

-- 
Ian Campbell
Current Noise: Akercocke - The Promise

Stult's Report:
	Our problems are mostly behind us.  What we have to do now is
	fight the solutions.