Re: [PATCH v2] vt: add init_hide parameter to suppress boot output
From: Greg Kroah-Hartman
Date: Tue Feb 19 2013 - 23:44:45 EST
On Tue, Feb 19, 2013 at 08:04:05PM -0800, Andy Ross wrote:
> On 02/19/2013 05:45 PM, Greg Kroah-Hartman wrote:
> >>When vt.init_hide is set, suppress output on newly created consoles
> >>until an affirmative switched to that console. This prevents boot
> >>output from displaying (and clobbering splash screens, etc...)
> >>without disabling the console entirely.
> >What's wrong with the 'quiet' option we have? And you forgot to
> >document this.
> You're right about docs, obviously. I'll write something up and send
> it tomorrow morning.
> But setting "quiet" controls logging. It won't prevent the console
> from doing a buffer clear or mode switch, nor will it prevent
> userspace from writing to it, nor will the buffer rewrites due to the
> console switches that happen on suspend and resume (which I didn't
> know existed) be suppressed.
> There's a (sort of) similar commonly-used option, vga=current, which
> prevents a mode switch for the special case of VGA/vesa. But that
> doesn't work with the framebuffer console.
Why not? Can't you fix that?
> The idea here (and I'm clearly no domain expert) was to leave the
> console enabled and active, but invisible by default. So nothing
> displays, the splash screen stays put, and nothing fights with other
> users of the framebuffer. And it stays that way until something
> affirmatively switches to a different VT using chvt or Alt-Fn or
> To be fair, a lot of this could be managed in userspace with the VT_*
> ioctl interface.
Yes, that's what "normal" systems do :)
> But the specific application here (Android's surfaceflinger) isn't set
> up for that, and it's a non-trivial API (and even doing it "right"
> involves racing against other users at startup).
How could there be any other users at startup, you "own" the system
here, there should not be anyone to race with.
> This seemed like a much simpler metaphor that still meets the
I think you should use the ioctls, that is what they are there for, and
is what you need to implement if you want to use a console anyway,
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/