Re: [PATCH v2 03/13] vt: Store font in struct vc_font

Hi

Am 03.03.26 um 15:31 schrieb Helge Deller:

On 3/2/26 15:08, Thomas Zimmermann wrote:

quoted

Replace struct console_font with struct vc_font for the type of the
vc_font field of struct vc_data. Struct console_font is UAPI, which
prevents further changes. Hence a new data type is required.

Struct console_font has a documented vertical pitch of 32 bytes. This
is not the case after the font data has been loaded into the kernel.
Changing the type of vc_font addresses this inconsistency.

The font data is now declared as constant, as it might come from the
kernel's read-only section. There's some fallout throughout the console
code where non-const variables refer to it. Fix them. A later update
will declare the font data to a dedicated data type.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  drivers/video/fbdev/core/bitblit.c | 11 +++++------
  drivers/video/fbdev/core/fbcon.c   |  4 ++--
  drivers/video/fbdev/core/fbcon.h   |  4 ++--
  include/linux/console_struct.h     | 29 +++++++++++++++++++++++++++--
  4 files changed, 36 insertions(+), 12 deletions(-)

....

quoted

diff --git a/include/linux/console_struct.h 

b/include/linux/console_struct.h
index ebdb9750d348..7fdcae6ed49c 100644

--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h

@@ -13,8 +13,9 @@

  #ifndef _LINUX_CONSOLE_STRUCT_H
  #define _LINUX_CONSOLE_STRUCT_H
  -#include <linux/wait.h>
+#include <linux/math.h>
  #include <linux/vt.h>
+#include <linux/wait.h>
  #include <linux/workqueue.h>
    struct uni_pagedict;

@@ -58,6 +59,30 @@ struct vc_state {

      bool        reverse;
  };
  +/**
+ * struct vc_font - Describes a font
+ * @width: The width of a single glyph in bits
+ * @height: The height of a single glyph in scanlines
+ * @charcount: The number of glyphs in the font
+ * @data: The raw font data
+ *
+ * Font data is organized as an array of glyphs. Each glyph is a 
bitmap with
+ * set bits indicating the foreground color. Unset bits indicate 
background
+ * color. The fields @width and @height store a single glyph's 
number of
+ * horizontal bits and vertical scanlines. If width is not a 
multiple of 8,
+ * there are trailing bits to fill up the byte. These bits should 
not be drawn.
+ *
+ * The field @data points to the first glphy's first byte. The value 
@charcount
+ * gives the number of glyphs in the font. There are no empty 
scanlines between
+ * two adjacent glyphs.
+ */
+struct vc_font {
+    unsigned int width;
+    unsigned int height;
+    unsigned int charcount;

I wonder if we shouldn't declare width and height as "u8" or "short 
int" type?
And charcount as u16 or "short int" ?
Makes later calculations shorter & easier.

That would be a change to vt and possibly affect a lot of consoles. In 
any case, I'd rather do this separately.

Best regards
Thomas

Helge

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)