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console: Make persistent scrollback a boot parameter 

The impact of the persistent scrollback feature on the code size is
rather small, so the config option is removed. The feature stays
disabled by default and can be enabled by using the boot command line
parameter 'vgacon.scrollback_persistent=1' or by setting
VGACON_SOFT_SCROLLBACK_PERSISTENT_ENABLE_BY_DEFAULT=y.

Signed-off-by: Manuel Schölling <manuel.schoelling@gmx.de>
Suggested-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Manuel Schölling 2017-01-13 21:07:58 +01:00 committed by Greg Kroah-Hartman
parent aabd31c421
commit 1a336c9346
2 changed files with 19 additions and 18 deletions
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12
drivers/video/console/Kconfig
View File

@ -47,14 +47,16 @@ config VGACON_SOFT_SCROLLBACK_SIZE
buffers of VGA consoles. Each 64KB will give you approximately
16 80x25 screenfuls of scrollback buffer.
config VGACON_SOFT_SCROLLBACK_PERSISTENT
bool "Persistent Scrollback History for each console"
config VGACON_SOFT_SCROLLBACK_PERSISTENT_ENABLE_BY_DEFAULT
bool "Persistent Scrollback History for each console by default"
depends on VGACON_SOFT_SCROLLBACK
default n
help
Say Y here if the scrollback history should persist when switching
between consoles. Otherwise, the scrollback history will be flushed
each time the console is switched.
Say Y here if the scrollback history should persist by default when
switching between consoles. Otherwise, the scrollback history will be
flushed each time the console is switched. This feature can also be
enabled using the boot command line parameter
'vgacon.scrollback_persistent=1'.
This feature might break your tool of choice to flush the scrollback
buffer, e.g. clear(1) will work fine but Debian's clear_console(1)

25
drivers/video/console/vgacon.c
View File

@ -174,11 +174,11 @@ struct vgacon_scrollback_info {
};
static struct vgacon_scrollback_info *vgacon_scrollback_cur;
#ifdef CONFIG_VGACON_SOFT_SCROLLBACK_PERSISTENT
static struct vgacon_scrollback_info vgacon_scrollbacks[MAX_NR_CONSOLES];
#else
static struct vgacon_scrollback_info vgacon_scrollbacks[1];
#endif
static bool scrollback_persistent = \
IS_ENABLED(CONFIG_VGACON_SOFT_SCROLLBACK_PERSISTENT_ENABLE_BY_DEFAULT);
module_param_named(scrollback_persistent, scrollback_persistent, bool, 0000);
MODULE_PARM_DESC(scrollback_persistent, "Enable persistent scrollback for all vga consoles");
static void vgacon_scrollback_reset(int vc_num, size_t reset_size)
{
@ -213,20 +213,19 @@ static void vgacon_scrollback_init(int vc_num)
static void vgacon_scrollback_switch(int vc_num)
{
#ifndef CONFIG_VGACON_SOFT_SCROLLBACK_PERSISTENT
vc_num = 0;
#endif
if (!scrollback_persistent)
vc_num = 0;
if (!vgacon_scrollbacks[vc_num].data) {
vgacon_scrollback_init(vc_num);
} else {
#ifdef CONFIG_VGACON_SOFT_SCROLLBACK_PERSISTENT
vgacon_scrollback_cur = &vgacon_scrollbacks[vc_num];
#else
size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
if (scrollback_persistent) {
vgacon_scrollback_cur = &vgacon_scrollbacks[vc_num];
} else {
size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
vgacon_scrollback_reset(vc_num, size);
#endif
vgacon_scrollback_reset(vc_num, size);
}
}
}