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Re: [Qemu-devel] [PATCH] hw: report invalid disable-legacy|modern usage
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH] hw: report invalid disable-legacy|modern usage for virtio-1-only devs |
Date: |
Mon, 28 Jan 2019 15:48:57 -0200 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Fri, Jan 18, 2019 at 01:38:26PM +0000, Daniel P. Berrangé wrote:
> A number of virtio devices (gpu, crypto, mouse, keyboard, tablet) only
> support the virtio-1 (aka modern) mode. Currently if the user launches
> QEMU, setting those devices to enable legacy mode, QEMU will silently
> create them in modern mode, ignoring the user's (mistaken) request.
>
> This patch introduces proper data validation so that an attempt to
> configure a virtio-1-only devices in legacy mode gets reported as an
> error to the user.
>
> Checking this required introduction of a new field to explicitly track
> what operating model is to be used for a device, separately from the
> disable_modern and disable_legacy fields that record the user's
> requested configuration.
>
> Signed-off-by: Daniel P. Berrangé <address@hidden>
This breaks the virtio-1-only devices on pc-*-2.6:
$ ./x86_64-softmmu/qemu-system-x86_64 -device virtio-vga -machine
pc-i440fx-2.6
qemu-system-x86_64: -device virtio-vga: Unable to set disable-legacy=off on a
virtio-1.0 only device
Probably the simplest way to fix that is to append the following to
hw_compat_2_6:
{ virtio-vga, disable-modern, off },
{ virtio-gpu-pci, disable-modern, off },
{ virtio-input-pci, disable-modern, off },
{ virtio-crypto-pci, disable-modern, off }
We could also remove the property completely from those devices
(e.g. by moving virtio-vga to virtio_vga_info.non_transitional_name),
but it would break compatibility in case people are explicitly
setting "disable-modern=off" on those devices.
--
Eduardo