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linux/include/linux/vt_kern.h
Mandeep Singh Baines c958474b6d panic, vt: do not force oops output when panic_timeout < 0 
Don't force output if you intend to reboot immediately.

In this patch, I'm disabling the functionality enabled by
vc->vc_panic_force_write if panic_timeout < 0 (i.e.  no timeout).
vc_panic_force_write is only enabled for fb video consoles if the
FBINFO_CAN_FORCE_OUTPUT flag is set.

For our application, we're using ram_oops to preserved the panic in
memory.  We want to reliably, and as fast as possible, machine_restart.
The vc_panic_force_write flag results in a bunch of graphics driver code
to be invoked which slows down restart and decreases reliability.  Since
we're already storing the panic in RAM and are going to reboot
immediately, there is no benefit in mode switching back to the vc in
order to display the panic output.  The log buffer will get flushed by
the console_unblank() call so remote management consoles should see all
output.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:45 -07:00

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#ifndef _VT_KERN_H
#define _VT_KERN_H
/*
* this really is an extension of the vc_cons structure in console.c, but
* with information needed by the vt package
*/
#include <linux/vt.h>
#include <linux/kd.h>
#include <linux/tty.h>
#include <linux/mutex.h>
#include <linux/console_struct.h>
#include <linux/mm.h>
#include <linux/consolemap.h>
#include <linux/notifier.h>
/*
* Presently, a lot of graphics programs do not restore the contents of
* the higher font pages. Defining this flag will avoid use of them, but
* will lose support for PIO_FONTRESET. Note that many font operations are
* not likely to work with these programs anyway; they need to be
* fixed. The linux/Documentation directory includes a code snippet
* to save and restore the text font.
*/
#ifdef CONFIG_VGA_CONSOLE
#define BROKEN_GRAPHICS_PROGRAMS 1
#endif
extern void kd_mksound(unsigned int hz, unsigned int ticks);
extern int kbd_rate(struct kbd_repeat *rep);
extern int fg_console, last_console, want_console;
/* console.c */
int vc_allocate(unsigned int console);
int vc_cons_allocated(unsigned int console);
int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines);
void vc_deallocate(unsigned int console);
void reset_palette(struct vc_data *vc);
void do_blank_screen(int entering_gfx);
void do_unblank_screen(int leaving_gfx);
void unblank_screen(void);
void poke_blanked_console(void);
int con_font_op(struct vc_data *vc, struct console_font_op *op);
int con_set_cmap(unsigned char __user *cmap);
int con_get_cmap(unsigned char __user *cmap);
void scrollback(struct vc_data *vc, int lines);
void scrollfront(struct vc_data *vc, int lines);
void update_region(struct vc_data *vc, unsigned long start, int count);
void redraw_screen(struct vc_data *vc, int is_switch);
#define update_screen(x) redraw_screen(x, 0)
#define switch_screen(x) redraw_screen(x, 1)
struct tty_struct;
int tioclinux(struct tty_struct *tty, unsigned long arg);
#ifdef CONFIG_CONSOLE_TRANSLATIONS
/* consolemap.c */
struct unimapinit;
struct unipair;
int con_set_trans_old(unsigned char __user * table);
int con_get_trans_old(unsigned char __user * table);
int con_set_trans_new(unsigned short __user * table);
int con_get_trans_new(unsigned short __user * table);
int con_clear_unimap(struct vc_data *vc, struct unimapinit *ui);
int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list);
int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct, struct unipair __user *list);
int con_set_default_unimap(struct vc_data *vc);
void con_free_unimap(struct vc_data *vc);
void con_protect_unimap(struct vc_data *vc, int rdonly);
int con_copy_unimap(struct vc_data *dst_vc, struct vc_data *src_vc);
#define vc_translate(vc, c) ((vc)->vc_translate[(c) | \
((vc)->vc_toggle_meta ? 0x80 : 0)])
#else
static inline int con_set_trans_old(unsigned char __user *table)
{
return 0;
}
static inline int con_get_trans_old(unsigned char __user *table)
{
return -EINVAL;
}
static inline int con_set_trans_new(unsigned short __user *table)
{
return 0;
}
static inline int con_get_trans_new(unsigned short __user *table)
{
return -EINVAL;
}
static inline int con_clear_unimap(struct vc_data *vc, struct unimapinit *ui)
{
return 0;
}
static inline
int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
{
return 0;
}
static inline
int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct,
struct unipair __user *list)
{
return -EINVAL;
}
static inline int con_set_default_unimap(struct vc_data *vc)
{
return 0;
}
static inline void con_free_unimap(struct vc_data *vc)
{
}
static inline void con_protect_unimap(struct vc_data *vc, int rdonly)
{
}
static inline
int con_copy_unimap(struct vc_data *dst_vc, struct vc_data *src_vc)
{
return 0;
}
#define vc_translate(vc, c) (c)
#endif
/* vt.c */
void vt_event_post(unsigned int event, unsigned int old, unsigned int new);
int vt_waitactive(int n);
void change_console(struct vc_data *new_vc);
void reset_vc(struct vc_data *vc);
extern int unbind_con_driver(const struct consw *csw, int first, int last,
int deflt);
int vty_init(const struct file_operations *console_fops);
static inline bool vt_force_oops_output(struct vc_data *vc)
{
if (oops_in_progress && vc->vc_panic_force_write && panic_timeout >= 0)
return true;
return false;
}
extern char vt_dont_switch;
extern int default_utf8;
extern int global_cursor_default;
struct vt_spawn_console {
spinlock_t lock;
struct pid *pid;
int sig;
};
extern struct vt_spawn_console vt_spawn_con;
extern int vt_move_to_console(unsigned int vt, int alloc);
/* Interfaces for VC notification of character events (for accessibility etc) */
struct vt_notifier_param {
struct vc_data *vc; /* VC on which the update happened */
unsigned int c; /* Printed char */
};
extern int register_vt_notifier(struct notifier_block *nb);
extern int unregister_vt_notifier(struct notifier_block *nb);
extern void hide_boot_cursor(bool hide);
#endif /* _VT_KERN_H */
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