Re: [Qemu-devel] [PATCH] pc: limit 64 bit hole to 2G by default

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 24 Jul 2013 12:51:16 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Wed, Jul 24, 2013 at 09:01:51AM +0200, Gerd Hoffmann wrote:
> > On 07/24/13 08:01, Michael S. Tsirkin wrote:
> > > It turns out that some 32 bit windows guests crash
> > > if 64 bit PCI hole size is >2G.
> > 
> > Ah, *that* is the reason for winxp crashing with a 64bit hole.
> > 
> > Current seabios uses a slightly different approach: the 64bit hole is
> > present only in case it is actually used to map bars there, and seabios
> > tries to fit everything into the 32bit hole first.
> 
> Yes. But this doesn't work with device hotplug.
> 
> > > Limit it to 2G for piix and q35 by default,
> > > add properties to let management override the hole size.
> > > 
> > > Examples:
> > > -global i440FX-pcihost.pci_hole64_size=137438953472
> > 
> > Do we really want specify this in bytes?  Using megabytes or gigabytes
> > instead looks more sane to me.
> > 
> > cheers,
> >   Gerd
> 
> I think that arbitrarily saying size is in gigabytes is
> confusing to users (in particular because there's no
> documentation for properties except their type).
> I intend to send a patch to properties that allows writing
> "size=1G" instead.
for size property you could take patches:
 [PATCH 04/16] qapi: make visit_type_size fallback to type_int
 [PATCH 05/16] qdev: Add SIZE type to qdev properties
from [PATCH 00/16 RFC v6] ACPI memory hotplug