![Michael Ellerman](/assets/img/avatar_default.png)
Currently printk is no use for early debugging because it refuses to actually print anything to the console unless cpu_online(smp_processor_id()) is true. The stated explanation is that console drivers may require per-cpu resources, or otherwise barf, because the system is not yet setup correctly. Fair enough. However some console drivers might be quite happy running early during boot, in fact we have one, and so it'd be nice if printk understood that. So I added a flag (which I would have called CON_BOOT, but that's taken) called CON_ANYTIME, which indicates that a console is happy to be called anytime, even if the cpu is not yet online. Tested on a Power 5 machine, with both a CON_ANYTIME driver and a bogus console driver that BUG()s if called while offline. No problems AFAICT. Built for i386 UP & SMP. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
139 lines
4.4 KiB
C
139 lines
4.4 KiB
C
/*
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* linux/include/linux/console.h
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*
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* Copyright (C) 1993 Hamish Macdonald
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*
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* Changed:
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* 10-Mar-94: Arno Griffioen: Conversion for vt100 emulator port from PC LINUX
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*/
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#ifndef _LINUX_CONSOLE_H_
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#define _LINUX_CONSOLE_H_ 1
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#include <linux/types.h>
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#include <linux/spinlock.h>
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struct vc_data;
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struct console_font_op;
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struct console_font;
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struct module;
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/*
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* this is what the terminal answers to a ESC-Z or csi0c query.
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*/
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#define VT100ID "\033[?1;2c"
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#define VT102ID "\033[?6c"
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struct consw {
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struct module *owner;
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const char *(*con_startup)(void);
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void (*con_init)(struct vc_data *, int);
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void (*con_deinit)(struct vc_data *);
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void (*con_clear)(struct vc_data *, int, int, int, int);
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void (*con_putc)(struct vc_data *, int, int, int);
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void (*con_putcs)(struct vc_data *, const unsigned short *, int, int, int);
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void (*con_cursor)(struct vc_data *, int);
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int (*con_scroll)(struct vc_data *, int, int, int, int);
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void (*con_bmove)(struct vc_data *, int, int, int, int, int, int);
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int (*con_switch)(struct vc_data *);
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int (*con_blank)(struct vc_data *, int, int);
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int (*con_font_set)(struct vc_data *, struct console_font *, unsigned);
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int (*con_font_get)(struct vc_data *, struct console_font *);
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int (*con_font_default)(struct vc_data *, struct console_font *, char *);
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int (*con_font_copy)(struct vc_data *, int);
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int (*con_resize)(struct vc_data *, unsigned int, unsigned int);
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int (*con_set_palette)(struct vc_data *, unsigned char *);
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int (*con_scrolldelta)(struct vc_data *, int);
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int (*con_set_origin)(struct vc_data *);
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void (*con_save_screen)(struct vc_data *);
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u8 (*con_build_attr)(struct vc_data *, u8, u8, u8, u8, u8);
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void (*con_invert_region)(struct vc_data *, u16 *, int);
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u16 *(*con_screen_pos)(struct vc_data *, int);
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unsigned long (*con_getxy)(struct vc_data *, unsigned long, int *, int *);
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};
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extern const struct consw *conswitchp;
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extern const struct consw dummy_con; /* dummy console buffer */
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extern const struct consw vga_con; /* VGA text console */
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extern const struct consw newport_con; /* SGI Newport console */
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extern const struct consw prom_con; /* SPARC PROM console */
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int take_over_console(const struct consw *sw, int first, int last, int deflt);
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void give_up_console(const struct consw *sw);
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/* scroll */
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#define SM_UP (1)
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#define SM_DOWN (2)
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/* cursor */
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#define CM_DRAW (1)
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#define CM_ERASE (2)
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#define CM_MOVE (3)
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/*
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* The interface for a console, or any other device that wants to capture
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* console messages (printer driver?)
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*
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* If a console driver is marked CON_BOOT then it will be auto-unregistered
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* when the first real console is registered. This is for early-printk drivers.
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*/
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#define CON_PRINTBUFFER (1)
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#define CON_CONSDEV (2) /* Last on the command line */
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#define CON_ENABLED (4)
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#define CON_BOOT (8)
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#define CON_ANYTIME (16) /* Safe to call when cpu is offline */
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struct console
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{
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char name[8];
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void (*write)(struct console *, const char *, unsigned);
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int (*read)(struct console *, char *, unsigned);
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struct tty_driver *(*device)(struct console *, int *);
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void (*unblank)(void);
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int (*setup)(struct console *, char *);
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short flags;
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short index;
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int cflag;
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void *data;
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struct console *next;
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};
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extern int add_preferred_console(char *name, int idx, char *options);
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extern void register_console(struct console *);
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extern int unregister_console(struct console *);
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extern struct console *console_drivers;
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extern void acquire_console_sem(void);
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extern int try_acquire_console_sem(void);
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extern void release_console_sem(void);
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extern void console_conditional_schedule(void);
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extern void console_unblank(void);
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extern struct tty_driver *console_device(int *);
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extern void console_stop(struct console *);
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extern void console_start(struct console *);
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extern int is_console_locked(void);
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/* Suspend and resume console messages over PM events */
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extern void suspend_console(void);
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extern void resume_console(void);
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/* Some debug stub to catch some of the obvious races in the VT code */
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#if 1
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#define WARN_CONSOLE_UNLOCKED() WARN_ON(!is_console_locked() && !oops_in_progress)
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#else
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#define WARN_CONSOLE_UNLOCKED()
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#endif
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/* VESA Blanking Levels */
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#define VESA_NO_BLANKING 0
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#define VESA_VSYNC_SUSPEND 1
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#define VESA_HSYNC_SUSPEND 2
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#define VESA_POWERDOWN 3
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#endif /* _LINUX_CONSOLE_H */
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