Re: [PATCH v3] console: Add persistent scrollback buffers for all VGA consoles

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Sep 19, 2016 at 12:06:57AM +0200, 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.
> 
> It always annoys me when I switch back to a console and I can just
> read half of an error backtrace. This should fix issues like these.
> 
> 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.
> 
> Signed-off-by: Manuel Schölling <manuel.schoelling@gmx.de>
> ---
> Changes in v3:
>   - Add config option for this feature
>   - Fallback to old scrollback buffer if kcalloc() fails
>   - Remove ioctl() call again and add documentation about existing
>     escape sequence to flush the scrollback buffer
> Changes in v2:
>   - Add ioctl() call to flush scrollback buffer
>   - (Patch v2 was not labeled as such, sorry)
> ---
>  drivers/video/console/Kconfig  |  23 +++++-
>  drivers/video/console/vgacon.c | 160 +++++++++++++++++++++++++++--------------
>  2 files changed, 128 insertions(+), 55 deletions(-)

I need someone else to at least test this, and give an acked-by for
it...

thanks,

greg k-h