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From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Dely Sy <dely.l.sy@intel.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	Rajat Jain <rajatxjain@gmail.com>,
	Guenter Roeck <groeck@juniper.net>,
	Kristen Carlson Accardi <kristen.c.accardi@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Praveen Kalamegham <praveen@nextio.com>
Subject: Re: Special handling of display/VGA devices in hotplug drivers
Date: Thu, 11 Dec 2014 22:57:18 +0000	[thread overview]
Message-ID: <20141211225718.403ada7e@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <CAErSpo4V8tYE+yHvQ+Se=tQHWAKafk89SmVTjeCVRzbA-VtQbg@mail.gmail.com>

> >> The PCI spec said that you were not allowed to hotplug VGA drivers.
> >> The big issue is that POST usually needs to run on those things, and
> >> there is no way to POST a PCI hotplugged device.
> 
> I don't think this is a problem any more, is it?  I think X can
> execute option ROMs, and if we assign the guest to a VM, the guest
> BIOS can also do it.

Providing the legacy I/O is routed to that device, it doesn't use DMA and
a few other things. X has been able to POST cards with vm86 or the 8086
emulator stuff for a long time (it had to in order to use most PC cards on
non x86 boxes).

Your bigger problem is the marvellous reliable way that X handles a GPU
simply vanishing, especially a legacy one.

Alan

      reply	other threads:[~2014-12-11 23:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-11 17:34 Bjorn Helgaas
2014-12-11 18:11 ` Greg Kroah-Hartman
2014-12-11 19:32   ` Jesse Barnes
2014-12-11 19:56     ` Guenter Roeck
2014-12-11 22:07     ` Bjorn Helgaas
2014-12-11 22:57       ` One Thousand Gnomes [this message]

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