Re: [Qemu-devel] [PATCH 1/7] vmgenid: replace x-write-pointer-available hack

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jul 03, 2017 at 03:50:52PM -0300, Eduardo Habkost wrote:
> On Mon, Jul 03, 2017 at 09:38:52PM +0300, Michael S. Tsirkin wrote:
> > On Thu, Jun 29, 2017 at 03:23:04PM +0200, Marc-André Lureau wrote:
> > > This compat property sole function is to prevent the device from being
> > > instantiated. Instead of requiring an extra compat property, check if
> > > fw_cfg has DMA enabled.
> > > 
> > > This has the additional benefit of handling other cases properly, like:
> > > 
> > >   $ qemu-system-x86_64 -device vmgenid -machine none
> > >   qemu-system-x86_64: -device vmgenid: vmgenid requires DMA write support in fw_cfg, which this machine type does not provide
> > >   $ qemu-system-x86_64 -device vmgenid -machine pc-i440fx-2.9 -global fw_cfg.dma_enabled=off
> > >   qemu-system-x86_64: -device vmgenid: vmgenid requires DMA write support in fw_cfg, which this machine type does not provide
> > >   $ qemu-system-x86_64 -device vmgenid -machine pc-i440fx-2.6 -global fw_cfg.dma_enabled=on
> > >   [boots normally]
> > > 
> > > Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
> > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> > 
> > It's a nice cleanup, but I suspect we need to first implement
> > a framework for initialization ordering. I don't much like it
> > that we are adding more dependencies to the current bag of hacks.
> 
> I agree we should address this, but in this case there's no need to
> introduce new mechanisms for initialization ordering if we just check
> the dependencies on machine_done notifier or acpi_setup() (which is
> called by machine_done).

I guess what should fail is attempt to register a writeable blob.
This sounds reasonable.

> -- 
> Eduardo