Re: [Qemu-devel] [PATCH v3 14/14] i386: ACPI table generation code from seabios

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v3 14/14] i386: ACPI table generation code from seabios
Date: Sun, 28 Jul 2013 10:00:27 +0300	[thread overview]
Message-ID: <20130728070027.GC12087@redhat.com> (raw)
In-Reply-To: <51F29615.7030900@redhat.com>

On Fri, Jul 26, 2013 at 05:30:29PM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> >> That's something I think that it's best for firmware to avoid.
> >> Much better to load tables in memory and use standard ACPI
> >> methods to find specific tables.
> > 
> > Problem is this happens relatively late in the firmware boot process.
> 
> Completely different idea to tackle the issue: use COMMAND_ADD_POINTER
> not only for table pointers, but also register offsets.  So the firmware
> doesn't need to parse fadt to figure how it should program pm_base, but
> instead can fixup the fadt according to the pm_base it has used.
> 
> That is more in line with how firmware works (pm_base and simliar things
> tends to be #defines and are not runtime-configurable).  And I think
> it's also more robust when extending/changing tables for newer acpi spec
> revisions.
> 
> cheers,
>   Gerd
> 

And for newer chipsets.  I agree. I plan to add a file to configure how
firmware programs PCI devices at init.

-- 
MST