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Commit a4bedd01 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
Browse files

vt: document vc_data by example 



All those members of vc_data are each explained in short. But it needs
an example for one to understand the whole picture.

So add an ascii art depicting the most important vc_data members.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1b0ec88a

include/linux/console_struct.h

+32 −0
Original line number Diff line number Diff line
@@ -21,6 +21,38 @@ struct uni_pagedir; 


#define NPAR 16



/*

 * Example: vc_data of a console that was scrolled 3 lines down.

 *

 *                              Console buffer

 * vc_screenbuf ---------> +----------------------+-.

 *                         | initializing W       |  \

 *                         | initializing X       |   |

 *                         | initializing Y       |    > scroll-back area

 *                         | initializing Z       |   |

 *                         |                      |  /

 * vc_visible_origin ---> ^+----------------------+-:

 * (changes by scroll)    || Welcome to linux     |  \

 *                        ||                      |   |

 *           vc_rows --->< | login: root          |   |  visible on console

 *                        || password:            |    > (vc_screenbuf_size is

 * vc_origin -----------> ||                      |   |   vc_size_row * vc_rows)

 * (start when no scroll) || Last login: 12:28    |  /

 *                        v+----------------------+-:

 *                         | Have a lot of fun... |  \

 * vc_pos -----------------|--------v             |   > scroll-front area

 *                         | ~ # cat_             |  /

 * vc_scr_end -----------> +----------------------+-:

 * (vc_origin +            |                      |  \ EMPTY, to be filled by

 *  vc_screenbuf_size)     |                      |  / vc_video_erase_char

 *                         +----------------------+-'

 *                         <---- 2 * vc_cols ----->

 *                         <---- vc_size_row ----->

 *

 * Note that every character in the console buffer is accompanied with an

 * attribute in the buffer right after the character. This is not depicted

 * in the figure.

 */

struct vc_data {

	struct tty_port port;			/* Upper level data */