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vgacon: remove software scrollback support

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Yunhai Zhang recently fixed a VGA software scrollback bug in commit
ebfdfeeae8 ("vgacon: Fix for missing check in scrollback handling"),
but that then made people look more closely at some of this code, and
there were more problems on the vgacon side, but also the fbcon software
scrollback.

We don't really have anybody who maintains this code - probably because
nobody actually _uses_ it any more.  Sure, people still use both VGA and
the framebuffer consoles, but they are no longer the main user
interfaces to the kernel, and haven't been for decades, so these kinds
of extra features end up bitrotting and not really being used.

So rather than try to maintain a likely unused set of code, I'll just
aggressively remove it, and see if anybody even notices.  Maybe there
are people who haven't jumped on the whole GUI badnwagon yet, and think
it's just a fad.  And maybe those people use the scrollback code.

If that turns out to be the case, we can resurrect this again, once
we've found the sucker^Wmaintainer for it who actually uses it.

Reported-by: NopNop Nop <nopitydays@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Cc: 张云海 <zhangyunhai@nsfocus.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds
2020-09-09 14:53:50 -07:00
parent 06a0df4d1b
commit 973c096f6a
6 changed files with 1 additions and 270 deletions
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drivers/video/console/Kconfig
-46
View File
@@ -22,52 +22,6 @@ config VGA_CONSOLE
Say Y.
config VGACON_SOFT_SCROLLBACK
bool "Enable Scrollback Buffer in System RAM"
depends on VGA_CONSOLE
default n
help
The scrollback buffer of the standard VGA console is located in
the VGA RAM. The size of this RAM is fixed and is quite small.
If you require a larger scrollback buffer, this can be placed in
System RAM which is dynamically allocated during initialization.
Placing the scrollback buffer in System RAM will slightly slow
down the console.
If you want this feature, say 'Y' here and enter the amount of
RAM to allocate for this buffer. If unsure, say 'N'.
config VGACON_SOFT_SCROLLBACK_SIZE
int "Scrollback Buffer Size (in KB)"
depends on VGACON_SOFT_SCROLLBACK
range 1 1024
default "64"
help
Enter the amount of System RAM to allocate for scrollback
buffers of VGA consoles. Each 64KB will give you approximately
16 80x25 screenfuls of scrollback buffer.
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 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)
will be broken, which might cause security issues.
You can use the escape sequence \e[3J instead if this feature is
activated.
Note that a buffer of VGACON_SOFT_SCROLLBACK_SIZE is taken for each
created tty device.
So if you use a RAM-constrained system, say N here.
config MDA_CONSOLE
depends on !M68K && !PARISC && ISA
tristate "MDA text console (dual-headed)"