drm/bochs: Use shadow buffer for bochs framebuffer console

The bochs driver (and virtual hardware) requires buffer objects to
reside in video ram to display them to the screen. So it can not
display the framebuffer console because the respective buffer object
is permanently pinned in system memory.

Using a shadow buffer for the console solves this problem. The console
emulation will pin the buffer object only during updates from the shadow
buffer. Otherwise, the bochs driver can freely relocated the buffer
between system memory and video ram.

v2:
	* select shadow FB via struct drm_mode_config.prefer_shadow_fbdev

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/315833/
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c
index bc19dbd531efc237b1407bcee204e28c52474d72..359030d5d818d0bef7b64a29267ca919d24cb1f9 100644 (file)
--- a/drivers/gpu/drm/bochs/bochs_kms.c
+++ b/drivers/gpu/drm/bochs/bochs_kms.c
@@ -191,6 +191,7 @@ int bochs_kms_init(struct bochs_device *bochs)
        bochs->dev->mode_config.fb_base = bochs->fb_base;
        bochs->dev->mode_config.preferred_depth = 24;
        bochs->dev->mode_config.prefer_shadow = 0;
+       bochs->dev->mode_config.prefer_shadow_fbdev = 1;
        bochs->dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
 
        bochs->dev->mode_config.funcs = &bochs_mode_funcs;