Re: [PATCH 1/9] drm/xen-front: Introduce Xen para-virtualized frontend driver

On 21/02/18 09:03, Oleksandr Andrushchenko wrote:

From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com

Introduce skeleton of the para-virtualized Xen display frontend driver. This patch only adds required essential stubs.

Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com

drivers/gpu/drm/Kconfig | 2 + drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/xen/Kconfig | 17 ++++++++ drivers/gpu/drm/xen/Makefile | 5 +++ drivers/gpu/drm/xen/xen_drm_front.c | 83 +++++++++++++++++++++++++++++++++++++ 5 files changed, 108 insertions(+) create mode 100644 drivers/gpu/drm/xen/Kconfig create mode 100644 drivers/gpu/drm/xen/Makefile create mode 100644 drivers/gpu/drm/xen/xen_drm_front.c

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index deeefa7a1773..757825ac60df 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -289,6 +289,8 @@ source "drivers/gpu/drm/pl111/Kconfig"

source "drivers/gpu/drm/tve200/Kconfig"

+source "drivers/gpu/drm/xen/Kconfig"

# Keep legacy drivers last

menuconfig DRM_LEGACY diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 50093ff4479b..9d66657ea117 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -103,3 +103,4 @@ obj-$(CONFIG_DRM_MXSFB) += mxsfb/ obj-$(CONFIG_DRM_TINYDRM) += tinydrm/ obj-$(CONFIG_DRM_PL111) += pl111/ obj-$(CONFIG_DRM_TVE200) += tve200/ +obj-$(CONFIG_DRM_XEN) += xen/ diff --git a/drivers/gpu/drm/xen/Kconfig b/drivers/gpu/drm/xen/Kconfig new file mode 100644 index 000000000000..4cca160782ab --- /dev/null +++ b/drivers/gpu/drm/xen/Kconfig @@ -0,0 +1,17 @@ +config DRM_XEN

• bool "DRM Support for Xen guest OS"
• depends on XEN
• help

•  Choose this option if you want to enable DRM support
  

•  for Xen.
  

+config DRM_XEN_FRONTEND

• tristate "Para-virtualized frontend driver for Xen guest OS"
• depends on DRM_XEN
• depends on DRM
• select DRM_KMS_HELPER
• select VIDEOMODE_HELPERS
• select XEN_XENBUS_FRONTEND
• help

•  Choose this option if you want to enable a para-virtualized
  

•  frontend DRM/KMS driver for Xen guest OSes.
  

diff --git a/drivers/gpu/drm/xen/Makefile b/drivers/gpu/drm/xen/Makefile new file mode 100644 index 000000000000..967074d348f6 --- /dev/null +++ b/drivers/gpu/drm/xen/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0

+drm_xen_front-objs := xen_drm_front.o

+obj-$(CONFIG_DRM_XEN_FRONTEND) += drm_xen_front.o diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c new file mode 100644 index 000000000000..fd372fb464a1 --- /dev/null +++ b/drivers/gpu/drm/xen/xen_drm_front.c @@ -0,0 +1,83 @@ +/*

• • Xen para-virtual DRM device
• • This program is free software; you can redistribute it and/or modify
• • it under the terms of the GNU General Public License as published by
• • the Free Software Foundation; either version 2 of the License, or
• • (at your option) any later version.
• • This program is distributed in the hope that it will be useful,
• • but WITHOUT ANY WARRANTY; without even the implied warranty of
• • MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• • GNU General Public License for more details.

Use SPDX identifier instead (same applies for all other new sources):

// SPDX-License-Identifier: GPL-2.0

• • Copyright (C) 2016-2018 EPAM Systems Inc.
• • Author: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com
• */

+#include <drm/drmP.h>

+#include <xen/platform_pci.h> +#include <xen/xen.h> +#include <xen/xenbus.h>

+#include <xen/interface/io/displif.h>

+static void backend_on_changed(struct xenbus_device *xb_dev,

• enum xenbus_state backend_state)
  

+{ +}

+static int xen_drv_probe(struct xenbus_device *xb_dev,

• const struct xenbus_device_id *id)
  

+{

• return 0;

+}

+static int xen_drv_remove(struct xenbus_device *dev) +{

• return 0;

+}

+static const struct xenbus_device_id xen_drv_ids[] = {

• { XENDISPL_DRIVER_NAME },
• { "" }

+};

+static struct xenbus_driver xen_driver = {

• .ids = xen_drv_ids,
• .probe = xen_drv_probe,
• .remove = xen_drv_remove,
• .otherend_changed = backend_on_changed,

+};

+static int __init xen_drv_init(void) +{

• if (!xen_domain())

• return -ENODEV;
  

• if (xen_initial_domain()) {

• DRM_ERROR(XENDISPL_DRIVER_NAME " cannot run in initial domain\n");
  

• return -ENODEV;
  

• }

Why not? Wouldn't that be possible in case of the backend living in a driver domain?

Juergen