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

[Eduardo Habkost]

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 <address@hidden>
> > Signed-off-by: Marc-André Lureau <address@hidden>
> 
> 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).

-- 
Eduardo