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 --- drivers/gpu/drm/bochs/bochs_kms.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c index bc19dbd531ef..359030d5d818 100644 --- 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;