On Tue, Feb 06, 2024 at 06:10:51PM +0800, Daniel van Vugt wrote: > Until now, deferred console takeover only meant defer until there is > output. But that risks stepping on the toes of userspace splash screens, > as console messages may appear before the splash screen. So check the > command line for the expectation of userspace splash and if present then > extend the deferral until after the first switch. > > V2: Added Kconfig option instead of hard coding "splash". > > Closes: https://bugs.launchpad.net/bugs/1970069 > Cc: Mario Limonciello <mario.limonciello@xxxxxxx> > Signed-off-by: Daniel van Vugt <daniel.van.vugt@xxxxxxxxxxxxx> > --- > drivers/video/console/Kconfig | 13 +++++++++++ > drivers/video/fbdev/core/fbcon.c | 38 ++++++++++++++++++++++++++++++-- > 2 files changed, 49 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig > index bc31db6ef7..a6e371bfb4 100644 > --- a/drivers/video/console/Kconfig > +++ b/drivers/video/console/Kconfig > @@ -138,6 +138,19 @@ config FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER > by the firmware in place, rather then replacing the contents with a > black screen as soon as fbcon loads. > > +config FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER_CONDITION > + string "Framebuffer Console Deferred Takeover Condition" > + depends on FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER > + default "splash" > + help > + If enabled this defers further the framebuffer console taking over > + until the first console switch has occurred. And even then only if > + text has been output, and only if the specified parameter is found > + on the command line. This ensures fbcon does not interrupt userspace > + splash screens such as Plymouth which may be yet to start rendering > + at the time of the first console output. "splash" is the simplest > + distro-agnostic condition for this that Plymouth checks for. Hm this seems a bit strange since a lot of complexity that no one needs, also my impression is that it's rather distro specific how you want this to work. So why not just a Kconfig option that lets you choose how much you want to delay fbcon setup, with the following options: - no delay at all - dely until first output from the console (which then works for distros which set a log-level to suppress unwanted stuff) - delay until first vt-switch. In that case I don't think we also need to delay for first output, since vt switch usually means you'll get first output right away (if it's a vt terminal) or you switch to a different graphical console (which will keep fbcon fully suppressed on the drm side). I think you could even reuse the existing CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER for this, and then just compile-time select which kind of notifier to register (well plus the check for "splash" on the cmdline for the vt switch one I guess). Thoughts? Cheers, Sima > + > config STI_CONSOLE > bool "STI text console" > depends on PARISC && HAS_IOMEM > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c > index 63af6ab034..98155d2256 100644 > --- a/drivers/video/fbdev/core/fbcon.c > +++ b/drivers/video/fbdev/core/fbcon.c > @@ -76,6 +76,7 @@ > #include <linux/crc32.h> /* For counting font checksums */ > #include <linux/uaccess.h> > #include <asm/irq.h> > +#include <asm/cmdline.h> > > #include "fbcon.h" > #include "fb_internal.h" > @@ -3358,6 +3359,26 @@ static int fbcon_output_notifier(struct notifier_block *nb, > > return NOTIFY_OK; > } > + > +#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER_CONDITION > +static int initial_console; > +static struct notifier_block fbcon_switch_nb; > + > +static int fbcon_switch_notifier(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct vc_data *vc = data; > + > + WARN_CONSOLE_UNLOCKED(); > + > + if (vc->vc_num != initial_console) { > + dummycon_unregister_switch_notifier(&fbcon_switch_nb); > + dummycon_register_output_notifier(&fbcon_output_nb); > + } > + > + return NOTIFY_OK; > +} > +#endif > #endif > > static void fbcon_start(void) > @@ -3370,7 +3391,16 @@ static void fbcon_start(void) > > if (deferred_takeover) { > fbcon_output_nb.notifier_call = fbcon_output_notifier; > - dummycon_register_output_notifier(&fbcon_output_nb); > +#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER_CONDITION > + if (cmdline_find_option_bool(boot_command_line, > + CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER_CONDITION)) { > + initial_console = fg_console; > + fbcon_switch_nb.notifier_call = fbcon_switch_notifier; > + dummycon_register_switch_notifier(&fbcon_switch_nb); > + } else > +#endif > + dummycon_register_output_notifier(&fbcon_output_nb); > + > return; > } > #endif > @@ -3417,8 +3447,12 @@ void __exit fb_console_exit(void) > { > #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER > console_lock(); > - if (deferred_takeover) > + if (deferred_takeover) { > dummycon_unregister_output_notifier(&fbcon_output_nb); > +#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER_CONDITION > + dummycon_unregister_switch_notifier(&fbcon_switch_nb); > +#endif > + } > console_unlock(); > > cancel_work_sync(&fbcon_deferred_takeover_work); > -- > 2.43.0 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
