Hi Adam, On Mo, 2016-11-21 at 21:17 +0100, Adam Borowski wrote: > On Sun, Nov 20, 2016 at 10:58:08PM +0100, Manuel Schölling wrote: > > Add a scrollback buffers for each VGA console. The benefit is that > > the scrollback history is not flushed when switching between consoles > > but is persistent. > > The buffers are allocated on demand when a new console is opened. > > > > This breaks tools like clear_console that rely on flushing the > > scrollback history by switching back and forth between consoles > > which is why this feature is disabled by default. > > Use the escape sequence \e[3J instead for flushing the buffer. > First, big thanks for this fix, it's something that greatly annoyed me > since forever! Yeah, me too! ;) > The thing about clear_console is unfortunate: they abused the bug you're > fixing. I've asked to use \e[3J (https://bugs.debian.org/845177) so there's > hope it'll be applied in stretch; with Debian configuring its glibc to > support only kernels from two releases before (in jessie that's 2.6.32, in > stretch 3.2)[1] there's hope we can flip the default in several years. > > Do you suspect any other program relies on VT switch to clear the > scrollback? Not, AFAIK. Although I do not have a complete list of programs that are suppose to do that. > But alas, this commit breaks that very \e[3J. It does only a \e[2J, leaving > the scrollback uncleared. For comparison, both mainline and with just your > preparatory commit, \e[3J works as expected. Really? All my tests worked fine: I compiled the kernel with the latest patches, started the kernel in QEMU and then did $ openvt /bin/sh $ echo -e '\e[3J' # scrollback buffer was flushed correctly $ chvt 2 $ echo -e '\e[3J' # scrollback buffer was flushed correctly Can you tell me how you tested it? Maybe I can reproduce the bug. Thanks for spending the time to test it! Bye, Manuel -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
