linux-toradex.git/drivers/video/console/vgacon.c, branch v5.0

vgacon: unconfuse vc_origin when using soft scrollback

2019-01-18T12:45:22+00:00

When CONFIG_VGACON_SOFT_SCROLLBACK is selected, the VGA display memory
index and vc_visible_origin don't change when scrollback is activated.
The actual screen content is saved away and the scrollbackdata is copied
over it. However the vt code, and /dev/vcs devices in particular, still
expect vc_origin to always point at the actual screen content not the
displayed scrollback content.

So adjust vc_origin to point at the saved screen content when scrollback
is active and set it back to vc_visible_origin when restoring the screen.

This fixes /dev/vcsa that return scrollback content when they
shouldn't (onli /dev/vcsa without a number should), and also fixes
/dev/vcsu that should return scrollback content when scrollback is
active but currently doesn't.

An unnecessary call to vga_set_mem_top() is also removed.

Signed-off-by: Nicolas Pitre 
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Greg Kroah-Hartman

video/console/vgacon: Print big fat warning with nomodeset

2018-07-24T17:11:26+00:00

It's been a pretty good while since kernel modesetting was introduced.
It has almost entirely replaced previous solutions which required
userspace modesetting, and I can't even recall any drivers off the top
of my head for modern day hardware that don't only support one or the
other. Even nvidia's ugly blob does not require the use of nomodeset,
and only requires that nouveau be blacklisted.

Effectively, the only thing nomodeset does in the year 2018 is disable
your graphics drivers. Since VESA is a thing, this will give many users
the false impression that they've actually fixed an issue they were
having with their machine simply because the laptop will boot up to a
degraded GUI. This of course, is never actually the case.

Things get even worse when you consider that there's still an enormous
amount of tutorials users find on the internet that still suggest adding
nomodeset, along with various users who have been around long enough to
still suggest it.

There really isn't any legitimate reason I can see for this to be an
option that's used by anyone else other then developers, or properly
informed users. So, let's end the confusion and start printing warnings
whenever it's enabled.

Signed-off-by: Lyude Paul 
Reviewed-by: Daniel Vetter 
Acked-by: Jani Nikula 
Cc: Kees Cook 
Cc: "Jan H. Schönherr" 
Cc: Bjorn Helgaas 
Signed-off-by: Bartlomiej Zolnierkiewicz

console: Expand dummy functions for CFI

2018-02-27T09:17:33+00:00

This expands the no-op dummy functions into full prototypes to avoid
indirect call mismatches when running under Control Flow Integrity
checking, like with Clang's -fsanitize=cfi.

Co-Developed-by: Sami Tolvanen 
Signed-off-by: Sami Tolvanen 
Signed-off-by: Kees Cook 
Signed-off-by: Greg Kroah-Hartman

vgacon: Set VGA struct resource types

2017-12-19T05:07:43+00:00

Set the resource type when we reserve VGA-related I/O port resources.

The resource code doesn't actually look at the type, so it inserts
resources without a type in the tree correctly even without this change.
But if we ever print a resource without a type, it looks like this:

  vga+ [??? 0x000003c0-0x000003df flags 0x0]

Setting the type means it will be printed correctly as:

  vga+ [io  0x000003c0-0x000003df]

Signed-off-by: Bjorn Helgaas

vgacon: Prevent faulty bootparams.screeninfo from causing harm

2017-09-04T14:00:50+00:00

If a zero for the number of colums or rows manages to slip through,
gotoxy() will underflow vc->vc_pos, causing the next action on the
referenced memory to end with a page fault.

Make the check in vgacon_startup() more pessimistic to prevent that.

Signed-off-by: Jan H. Schönherr 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Signed-off-by: Bartlomiej Zolnierkiewicz

console: Make persistent scrollback a boot parameter

2017-01-25T10:54:02+00:00

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 
Suggested-by: Bartlomiej Zolnierkiewicz 
Signed-off-by: Greg Kroah-Hartman

console: Add persistent scrollback buffers for all VGA consoles

2017-01-25T10:54:02+00:00

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.

Signed-off-by: Manuel Schölling 
Reviewed-by: Andrey Utkin 
Tested-by: Andrey Utkin 
Tested-by: Adam Borowski 
Signed-off-by: Greg Kroah-Hartman

console: Add callback to flush scrollback buffer to consw struct

2017-01-25T10:54:02+00:00

This new callback is in preparation for persistent scrollback buffer
support for VGA consoles.
With a single scrollback buffer for all consoles, we could flush the
buffer just by invocating consw->con_switch(). But when each VGA console
has its own scrollback buffer, we need a new callback to tell the
video console driver which buffer to flush.

Signed-off-by: Manuel Schölling 
Reviewed-by: Andrey Utkin 
Tested-by: Andrey Utkin 
Tested-by: Adam Borowski 
Signed-off-by: Greg Kroah-Hartman

console: Move scrollback data into its own struct

2017-01-25T10:54:02+00:00

This refactoring is in preparation for persistent scrollback
support for VGA console.

Signed-off-by: Manuel Schölling 
Reviewed-by: Andrey Utkin 
Tested-by: Andrey Utkin 
Tested-by: Adam Borowski 
Signed-off-by: Greg Kroah-Hartman

vgacon: remove prehistoric macros

2016-10-27T14:37:44+00:00

These macros:
* CAN_LOAD_EGA_FONTS
* CAN_LOAD_PALETTE
* TRIDENT_GLITCH
* VGA_CAN_DO_64KB
* SLOW_VGA
are either always set or always unset. They come from the linux 2.1
times. And given nobody switched them to some configurable options, I
assume nobody actually uses them.

So remove the macros and leave in place appropriate branches of the
conditional code.

Signed-off-by: Jiri Slaby 
Cc: Tomi Valkeinen 
Cc: 
Cc: 
Signed-off-by: Greg Kroah-Hartman