On Thu 2018-12-20 17:31:57, Bartlomiej Zolnierkiewicz wrote:
>
> [ added Petr & Sergey to Cc: ]
>
> Hi,
>
> On 10/30/2018 04:44 PM, Prarit Bhargava wrote:
> > On text-based systems the 'quiet' boot option will show printk levels
> > higher than CONSOLE_LOGLEVEL_QUIET. The displaying of the Tux logo
> > during boot can cause some consoles to lose display data and as a result
> > confuse the end user.
> >
> > Do not display the Tux logo on systems that are in 'quiet' boot.
> >
> > v2: It helps to commit all my changes before sending them. Remove extra
> > bracket.
> > v3: buildbot error fix: fbcon can be built as part of a module so export console_printk
> >
> > Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
> > Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
> > Cc: Marko Myllynen <myllynen@xxxxxxxxxx>
> > Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> > Cc: Thierry Reding <treding@xxxxxxxxxx>
> > Cc: Yisheng Xie <ysxie@xxxxxxxxxxx>
> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > ---
> > drivers/video/fbdev/core/fbcon.c | 13 ++++++++-----
> > kernel/printk/printk.c | 1 +
> > 2 files changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> > index 8958ccc8b1ac..08e092eaf45c 100644
> > --- a/drivers/video/fbdev/core/fbcon.c
> > +++ b/drivers/video/fbdev/core/fbcon.c
> > @@ -649,11 +649,14 @@ static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info,
> > kfree(save);
> > }
> >
> > + if (logo_shown == FBCON_LOGO_DONTSHOW)
> > + return;
> > +
> > if (logo_lines > vc->vc_bottom) {
> > logo_shown = FBCON_LOGO_CANSHOW;
> > printk(KERN_INFO
> > "fbcon_init: disable boot-logo (boot-logo bigger than screen).\n");
> > - } else if (logo_shown != FBCON_LOGO_DONTSHOW) {
> > + } else {
> > logo_shown = FBCON_LOGO_DRAW;
> > vc->vc_top = logo_lines;
> > }
> > @@ -1051,7 +1054,7 @@ static void fbcon_init(struct vc_data *vc, int init)
> > struct vc_data **default_mode = vc->vc_display_fg;
> > struct vc_data *svc = *default_mode;
> > struct display *t, *p = &fb_display[vc->vc_num];
> > - int logo = 1, new_rows, new_cols, rows, cols, charcnt = 256;
> > + int new_rows, new_cols, rows, cols, charcnt = 256;
> > int cap, ret;
> >
> > if (info_idx == -1 || info == NULL)
> > @@ -1059,9 +1062,9 @@ static void fbcon_init(struct vc_data *vc, int init)
> >
> > cap = info->flags;
> >
> > - if (vc != svc || logo_shown == FBCON_LOGO_DONTSHOW ||
> > + if (vc != svc || console_loglevel <= CONSOLE_LOGLEVEL_QUIET ||
> > (info->fix.type == FB_TYPE_TEXT))
> > - logo = 0;
> > + logo_shown = FBCON_LOGO_DONTSHOW;
>
> "logo" variable removal is an unrelated change which actually
> changes the code behavior ("logo_shown" will be now modified
> also for "vc != svc" and "info->fix.type == FB_TYPE_TEXT" cases).
>
> Please either drop it or explain in the patch description why
> it is a safe thing to do.
Good question! I am not familiar with fbcon code but it seems
that there might be more instances and they share the behavior
via this variable.
Note that console_loglevel might get modified at anytime. What if
the first fbcon was initialized with a different loglevel?
> > if (var_to_display(p, &info->var, info))
> > return;
> > @@ -1176,7 +1179,7 @@ static void fbcon_init(struct vc_data *vc, int init)
> > } else
> > vc_resize(vc, new_cols, new_rows);
> >
> > - if (logo)
> > + if (logo_shown != FBCON_LOGO_DONTSHOW)
> > fbcon_prepare_logo(vc, info, cols, rows, new_cols, new_rows);
> >
> > if (vc == svc && softback_buf)
> > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> > index b77150ad1965..391e390feac9 100644
> > --- a/kernel/printk/printk.c
> > +++ b/kernel/printk/printk.c
> > @@ -66,6 +66,7 @@ int console_printk[4] = {
> > CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */
> > CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */
> > };
> > +EXPORT_SYMBOL(console_printk);
>
> You need printk Maintainers Ack on it.
I am fine with the added export (as a printk maintainer).
Best Regards,
Petr
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