[3/3] VT: Bump font size limitation to 64x128 pixels
Commit Message
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>
Comments
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@ens-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,
Jiri Slaby, le mar. 06 déc. 2022 07:48:37 +0100, a ecrit:
> 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@ens-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.
Oh, indeed, I'll fix that as well.
Thanks,
Samuel
===================================================================
@@ -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)
static int con_font_get(struct vc_data *vc, struct console_font_op *op)
{
@@ -4645,9 +4648,10 @@ static int con_font_set(struct vc_data *
return -EINVAL;
if (!op->data)
return -EINVAL;
- if (op->charcount > 512)
+ if (op->charcount > max_font_glyphs)
return -EINVAL;
- if (op->width <= 0 || op->width > 32 || !op->height || op->height > 32)
+ if (op->width <= 0 || op->width > max_font_width || !op->height ||
+ op->height > max_font_height)
return -EINVAL;
if (vpitch < op->height)
return -EINVAL;
===================================================================
@@ -1203,7 +1203,7 @@ sisusbcon_font_set(struct vc_data *c, st
struct sisusb_usb_data *sisusb;
unsigned charcount = font->charcount;
- if (font->width != 8 || vpitch != 32 ||
+ if (font->width != 8 || font->height > 32 || vpitch != 32 ||
(charcount != 256 && charcount != 512))
return -EINVAL;
===================================================================
@@ -1037,7 +1037,7 @@ static int vgacon_font_set(struct vc_dat
if (vga_video_type < VIDEO_TYPE_EGAM)
return -EINVAL;
- if (font->width != VGA_FONTWIDTH || vpitch != 32 ||
+ if (font->width != VGA_FONTWIDTH || font->height > 32 || vpitch != 32 ||
(charcount != 256 && charcount != 512))
return -EINVAL;
===================================================================
@@ -2279,6 +2279,8 @@ static int fbcon_get_font(struct vc_data
font->width = vc->vc_font.width;
font->height = vc->vc_font.height;
+ if (font->height > vpitch)
+ return -ENOSPC;
font->charcount = vc->vc_hi_font_mask ? 512 : 256;
if (!font->data)
return 0;