Re: [Qemu-devel] [PATCH v2] Sort the fw_cfg file list

[Michael S. Tsirkin]

On Wed, Mar 16, 2016 at 10:21:07AM -0500, Corey Minyard wrote:
> On 03/15/2016 12:01 PM, Michael S. Tsirkin wrote:
> >On Tue, Mar 15, 2016 at 11:36:39AM -0500, Corey Minyard wrote:
> >
> >>I've hit a bit of a snag here.  For 0.11 and before, PCI option ROMs
> >>were loaded via fw_cfg, not in the PCI ROM BAR.  This causes two
> >>issues:
> >>
> >>* The order depends on the device initialization order,
> >>which I'm not sure is quantifiable.  I believe it depends on
> >>how they are listed on the command line.
> >>
> >>* Users can load their own romfile with their own name, which
> >>means it can't be in the list.
> >>
> >>Also, for the ISA VGA ROMs, their order will also depend on the
> >>device list order.
> >>
> >>Outside of that, I have an order of file names.
> >>
> >>I think if I treat the device ROMs separately and handle them
> >>in init order, and then stick that device list in the proper location,
> >>that will work.  Does that sound reasonable?
> >>
> >>Thanks,
> >>
> >>-corey
> >I think so. By the time this becomes an issue we might decide to
> >disable migration from 0.11
> >
> 
> One more thing here.  I've realized that this is used for
> non-x86, too, and I'm wondering how much those matter.
> It's going to be really hard to figure out an order for these,
> as different boards/arches use the same names and install
> them in different orders.
> 
> For legacy mode, can I just put them in order for non-x86?
> Is there an easy way to detect that you are running x86?
> 
> -corey

We only care about the order because of ability to migrate
guests between QEMU versions.
Only architectures that version their machine types support this.

AFAIK at this point this means x86 and s390.

-- 
MST