linux-kernel - Re: [patch 3/3] VT: Bump font size limitation to 64x128 pixels

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Message-ID: <45c09e48-9e69-2371-70d2-8a0b1e9f4899@kernel.org>
Date:   Tue, 6 Dec 2022 07:48:37 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Samuel Thibault <samuel.thibault@...-lyon.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kbd@...ts.altlinux.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [patch 3/3] VT: Bump font size limitation to 64x128 pixels

On 05. 12. 22, 1:07, Samuel Thibault wrote:
> This moves 32x32 font size limitation checking down to drivers, so that
> fbcon can allow large fonts.
> 
> We still keep a limitation to 64x128 pixels so as to have a simple bounded
> allocation for con_font_get and in the userland kbd tool. That glyph size
> will however be enough to have 128x36 characters on a "16/9 8K display".
> 
> Signed-off-by: Samuel Thibault <samuel.thibault@...-lyon.org>
> 
> Index: linux-6.0/drivers/tty/vt/vt.c
> ===================================================================
> --- linux-6.0.orig/drivers/tty/vt/vt.c
> +++ linux-6.0/drivers/tty/vt/vt.c
> @@ -4575,17 +4575,20 @@ void reset_palette(struct vc_data *vc)
...
> -#define max_font_size 65536
> +#define max_font_width	64
> +#define max_font_height	128
> +#define max_font_glyphs	512
> +#define max_font_size	(max_font_glyphs*max_font_width*max_font_height)

So this is 64K -> 4M switch. We should likely convert to kvmalloc() too.

regards,
-- 
js
suse labs