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For user-provided fonts, the framebuffer layer is using a magic
negative-indexing macro, FNTCHARCNT(), to keep track of their number of
characters:
#define FNTCHARCNT(fd) (((int *)(fd))[-3])
For built-in fonts, it is using hard-coded values (256). This results in
something like the following:
map.length = (ops->p->userfont) ?
FNTCHARCNT(ops->p->fontdata) : 256;
This is unsatisfactory. In fact, there is already a `charcount` field in
our virtual console descriptor (see `struct console_font` inside `struct
vc_data`), let us use it:
map.length = vc->vc_font.charcount;
Recently we added a `charcount` field to `struct font_desc`. Use it to set
`vc->vc_font.charcount` properly. The idea is:
- We only use FNTCHARCNT() on `vc->vc_font.data` and `p->fontdata`.
Assume FNTCHARCNT() is working as intended;
- Whenever `vc->vc_font.data` is set, also set `vc->vc_font.charcount`
properly;
- We can now replace `FNTCHARCNT(vc->vc_font.data)` with
`vc->vc_font.charcount`;
- Since `p->fontdata` always point to the same font data buffer with
`vc->vc_font.data`, we can also replace `FNTCHARCNT(p->fontdata)` with
`vc->vc_font.charcount`.
In conclusion, set `vc->vc_font.charcount` properly in fbcon_startup(),
fbcon_init(), fbcon_set_disp() and fbcon_do_set_font(), then replace
FNTCHARCNT() with `vc->vc_font.charcount`. No more if-else between
negative-indexing macros and hard-coded values.
Do not include <linux/font.h> in fbcon_rotate.c and tileblit.c, since they
no longer need it.
Depends on patch "Fonts: Add charcount field to font_desc".
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/e460a5780e54e3022661d5f09555144583b4cc59.1605169912.git.yepeilin.cs@gmail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.