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

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 03.03.26 um 15:31 schrieb Helge Deller:
> On 3/2/26 15:08, Thomas Zimmermann wrote:
>> 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(-)
>>
> ....
>> 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)