From: Alexey Gladkov <legion@kernel.org> To: Samuel Thibault <samuel.thibault@ens-lyon.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jirislaby@kernel.org>, kbd@lists.altlinux.org, linux-kernel@vger.kernel.org Subject: Re: [kbd] [patchv2 3/3] VT: Bump font size limitation to 64x128 pixels Date: Sun, 18 Dec 2022 16:25:01 +0100 Message-ID: <Y58wzU081UB1IsxB@example.org> (raw) In-Reply-To: <20221218145532.syqzu76q23rz4tx6@begin> On Sun, Dec 18, 2022 at 03:55:32PM +0100, Samuel Thibault wrote: > Hello, > > Alexey Gladkov, le dim. 18 déc. 2022 15:39:38 +0100, a ecrit: > > On Sun, Dec 18, 2022 at 01:32:12AM +0100, 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@ens-lyon.org> > > > > > > --- > > > V1 -> V2: Switch con_font_get to kvmalloc/kvfree instead of kmalloc/kfree > > > > > > 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) > > > /* > > > * Font switching > > > * > > > - * Currently we only support fonts up to 32 pixels wide, at a maximum height > > > - * of 32 pixels. Userspace fontdata is stored with 32 bytes (shorts/ints, > > > - * depending on width) reserved for each character which is kinda wasty, but > > > - * this is done in order to maintain compatibility with the EGA/VGA fonts. It > > > - * is up to the actual low-level console-driver convert data into its favorite > > > - * format (maybe we should add a `fontoffset' field to the `display' > > > - * structure so we won't have to convert the fontdata all the time. > > > + * Currently we only support fonts up to 128 pixels wide, at a maximum height > > > + * of 128 pixels. Userspace fontdata may have to be stored with 32 bytes > > > + * (shorts/ints, depending on width) reserved for each character which is > > > + * kinda wasty, but this is done in order to maintain compatibility with the > > > + * EGA/VGA fonts. It is up to the actual low-level console-driver convert data > > > + * into its favorite format (maybe we should add a `fontoffset' field to the > > > + * `display' structure so we won't have to convert the fontdata all the time. > > > * /Jes > > > */ > > > > > > -#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) > > > > As a suggestion that you can safely ignore. Maybe make max_font_glyphs a > > sysctl parameter to be able to use larger fonts ? > > > > I get requests from time to time in kbd that it is not possible to load a > > larger font. > > 64KiB was really low, while the theoretically possible max was > 32*32*512 = 512KB, so I understand there used to be such requests :) > > Here, by setting the max to 64x128*512, I don't think we'll need more. I was not talking about the size of one glyph, but about the number of glyphs in the font. Right now the font cannot have more than 512 glyphs. > Even with a 8K screen (will such really exist and want a text console?) > the max 64x128 gets 128 characters on a single line, for soemthing like > 36 lines. So I guess it's not worth adding yet another sysctl :) Ok. > Samuel > -- Rgrds, legion
next prev parent reply other threads:[~2022-12-18 15:25 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-12-18 0:32 [kbd] [patchv2 0/3] VT: Support >32x32 fonts for hidpi displays Samuel Thibault 2022-12-18 0:32 ` [kbd] [patchv2 1/3] VT: Add height parameter to con_font_get/set consw operations Samuel Thibault 2023-01-19 15:09 ` Greg Kroah-Hartman 2023-01-19 15:20 ` Samuel Thibault 2022-12-18 0:32 ` [kbd] [patchv2 2/3] VT: Add KD_FONT_OP_SET/GET_TALL operations Samuel Thibault 2022-12-18 0:32 ` [kbd] [patchv2 3/3] VT: Bump font size limitation to 64x128 pixels Samuel Thibault 2022-12-18 14:39 ` Alexey Gladkov 2022-12-18 14:55 ` Samuel Thibault 2022-12-18 15:25 ` Alexey Gladkov [this message] 2022-12-18 15:28 ` Samuel Thibault 2022-12-18 15:38 ` Alexey Gladkov 2023-01-19 14:55 ` Greg Kroah-Hartman 2022-12-18 0:33 ` [kbd] [patch] font: Leverage KD_FONT_OP_GET/SET_TALL font operations Samuel Thibault 2023-01-11 20:00 ` Alexey Gladkov 2023-01-16 22:44 ` Samuel Thibault 2023-01-10 20:55 ` [kbd] [patchv2 0/3] VT: Support >32x32 fonts for hidpi displays Samuel Thibault 2023-01-18 14:00 ` Alexey Gladkov
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